Persistent aerial communication and control system

ABSTRACT

Systems and methods for powering and controlling flight of an unmanned aerial vehicle are provided. The unmanned aerial vehicles can be used in a networked communication system. A tether management system can be used to facilitate both mobile and static tethered operation to provide power and/or voice and data communication.

CROSS REFERENCE FOR RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/US2018/053226 filed Sep. 27, 2018, which claims priority to U.S.Application No. 62/564,175 filed Sep. 27, 2017 and to U.S. ApplicationNo. 62/672,366 filed May 16, 2018. This application is acontinuation-in-part of U.S. application Ser. No. 16/349,146 filed May10, 2019, which is a U.S. National Stage Application under 35 U.S.C. §371 of International Application No. PCT/US2017/061195 filed Nov. 10,2017, which claims priority to U.S. Application No. 62/564,175 filedSep. 27, 2017, and to U.S. Application No. 62/420,548 filed on Nov. 10,2016, and to U.S. Application No. 62/463,536 filed on Feb. 24, 2017.International Application No. PCT/US2017/061195 is acontinuation-in-part of International Application No. PCT/US2017/024152filed Mar. 24, 2017, which claims priority to U.S. Application No.62/312,887 filed on Mar. 24, 2016, and to U.S. Application No.62/315,873 filed Mar. 31, 2016, and to U.S. Application No. 62/321,292filed Apr. 12, 2016, and to U.S. Application No. 62/420,548 filed onNov. 10, 2016, and to U.S. Application No. 62/463,536 filed on Feb. 24,2017. The entire contents of the above referenced applications beingincorporated herein by reference.

TECHNICAL FIELD

One or more embodiments relate generally to unmanned aerial vehicles andmore particularly, for example, to persistent aerial communication andcontrol system.

BACKGROUND

Unmanned aerial vehicles (UAVs) such as aerial drones may be utilized ina variety of settings. For example, UAVs may be employed to performreconnaissance and observation tasks through the use of onboard sensors.These sensors may include a variety of imaging devices that may be usedto acquire data regarding objects and/or locations of interest.Depending upon the type of drone and the mission, the acquired data maythen be transmitted to a ground station, either in real-time, at missionend or, on occasion, on a delayed basis while in operation such as whilestill in transit returning from a mission area. Many UAVs are designedto fly or hover during their reconnaissance or observation missionswhile powered by an onboard battery which is required to supply powerfor both propulsion, onboard sensors and other electronics. The batterylife therefore provides a maximum mission length for the UAV. Other UAVshave been configured to be powered via a microfilament deployed from aground location during their operation thereby extending mission lengthwhile restricting the mission flight area in most cases based on thelength of the filament.

A continuing needs, exists however, for improvements in the design ofunmanned aerial vehicles for a variety of applications.

SUMMARY

The present invention relates to systems and operational methods forunmanned aerial vehicles (UAVs). Embodiments can include controlledoperation of tethered aerial vehicles with which power, control andcommunication signals are transmitted to the aerial vehicle. The controlstation and aerial vehicle include power management systems and controlcircuits to control takeoff, flight operation and landing of thevehicle. One or more data processors located with the control station,on the aerial vehicle or connected by a communications network areconfigured to execute instructions to operate the system. The one ormore UAVs can operate for radio transmission and reception of cellularcommunication or as an internet portal.

In one embodiment, a UAV may draw power from either remote sources (viatether), from on-board batteries, or from both, as required by operatorcommand or by autonomous control. This ability allows, among otherfeatures, a ground-powered or water based aerial vehicle to have a powersource for safe, controlled landings upon interruption of a tetheredpower source.

Systems and methods of preferred embodiments comprise a tethermanagement system having high deployment and retrieval rate. A staticassembly can be used on which the tether can be positioned fordeployment and retrieval. A moveable actuator contacts the tether toseparate the tether from the static assembly during deployment orretrieval in response to commands from a control system that responds toboth manual and stored instructions to coordinate tether management withUAV flight control functions. The UAV can employ an inertial navigationon the vehicle to provide autonomous flight control functions. A GPSsensor on the vehicle can update the vehicle position and is used fornavigation. Preferred embodiments employ devices and methods to updatelocation data of the aerial vehicle in the event a GPS signal is notdetected by aerial vehicle for a preset period of time. Thus, redundantposition identification systems are used for a variety of operatingenvironments.

A preferred embodiment uses radar data from an external radar system toprovide updated position data to the vehicle. A further embodiment usesan optical system to determine aerial vehicle position. Such a systemcan utilize light emitters or emitter arrays a control station, on theaerial vehicle or mounted on a tether connected to the vehicle. Lightdetectors can measure distance and location within a field of view suchas by LIDAR or other known techniques.

The management of a tether (e.g., for power, communication, and/orphysical attachment) connected to an Unmanned Aerial Vehicle (UAV)requires special considerations in order to minimize tangling, decreasethe risk of breakage, and minimize UAV power consumption. There are anumber of different physical attributes of the tether that can bemanaged, with tension management being an important attribute. Inparticular a specific tension may need to be maintained at times (e.g.,during flight) with the exception of launching and landing. Keepingoptimal tension on the tether during flight prevents it from excessivebowing under wind load and reduces the risk of contacting the ground orother obstacles, while also preventing the tension from being too greatfor the UAV to lift. The optimal magnitude of the tension may bedependent on other factors during the flight, such as altitude and airspeed (combination of wind and ground speed).

Further, there are many methods of winding a tether. In some examples, aspool is mounted on an arbor, with the spool being rotated by a motor.Because the spool rotates and in doing so, introduces relative motionbetween the moving spool and the chassis, a slip ring is used internalto the arbor to pass power and/or communication signals. This rotatingconnection prevents the wires from twisting as the arbor and spool arerotated.

Some spooler approaches include a force sensor which measures thetension in the tether, and a motor driven pinch roller which feedstether in or out as needed to maintain a proper amount of tension. Suchapproaches may include a spring arm on the output which includes anangle sensor that in turn, provides additional information to thecontrol algorithm.

From the pinch roller, the tether travels over a pulley mounted on anarm which is free to rotate about the opposite end. An angle sensor isable to detect the position of the arm. This position is used tocalculate the velocity of the spindle motor, which controls the rotationof the spool. This mechanism is sometimes referred to as the “dancer”.Certain embodiments do not require a dancer or pinch roller system asset forth in greater detail herein.

As the air vehicle ascends, the tension sensor detects an increase intension, and commands the pinch rollers to feed out tether to reduce thetension in the tether. This causes the dancer to lift, which in turncauses the spool motor to feed out the tether. As the UAV descends, thetension sensor sees the tension drop, and commands the pinch rollers topull in the tether until the desired tension is met. This causes thedancer to fall, which in turn, causes the spindle motor to retract thetether. Because the spool is a relatively small diameter and contains arelatively long length of tether, a level winding traverse is used tomanage the wind pattern on the spool.

Such approaches can include a drive motor; a toothed belt; a spindleassembly (including bearing, shafts, mercury slip ring, connectors); aspool; a traverse winding assembly (including a stepper motor; limitswitches; linear bearing system, pinch rollers, a tension sensor, andcustom pulleys); a load cell force meter; and the dancer assemblyincluding springs, one or more encoders, and pulleys.

Aspects described herein decrease the number of working parts needed fortether management, reduce the risk of mechanical failure, and reducemanufacturing complexity and cost. Aspects may enable addition offiber-optic cable to the tether, which can be damaged by the small bendradius used in of prior spooler designs.

In the described aspects, the spool is stationary, and a motor wraps thetether around the spool. This eliminates the need for a slip ring tomanage line twist. Because the spool is much larger than before, thetraverse is no longer needed to manage the pattern of winding. Alsobecause the spool is much larger, the need to actively cool the tetheron the spool is reduced. Embodiments of the spool can include anystructure that enables rapid deployment and retrieval within a confinedspace.

In a general aspect, a spooling apparatus includes a chassis, a spoolretainer configured to fixably retain a spool on the chassis, the spoolhaving a central axis and being configured to have a tether woundthereon and a winding mechanism. The winding mechanism includes a motormounted to the chassis, the motor being coupled to a driving elementcoaxially aligned with a central axis of the spool, a spring coupled tothe driving element of the motor, and a winding arm coupled to thedriving element via the spring. Rotation of the motor causes rotation ofthe driving element, the spring, and the winding arm to deploy thetether from the spool. The spooling apparatus also includes a controllerfor controlling the winding mechanism to maintain tension on thedeployed spool at a desired tension.

The spooling apparatus may include the spool with the tether woundthereon. The spool may be rotatably fixed or otherwise staticallyattached relative to the chassis or system housing. The controller maybe configured to infer an actual tension on the tether according to adeflection of the spring. The winding mechanism may include a firstencoder mounted on the driving element for measuring a first angularposition of the driving element relative to the chassis and a secondencoder mounted on the winding arm for measuring a second angularposition of the winding arm relative to the chassis. The deflection ofthe spring may be determined as a difference between the first angularposition and the second angular position.

A distal end of the winding arm may include a first pulley for receivingtether from the spool. The spooling apparatus may include a secondpulley disposed substantially in the center of the spool, the secondpulley being configured to receive tether from the first pulley and todeploy or re-spool the received tether. The spooling apparatus mayinclude a ring bearing coupling the spring to the winding arm.

Preferred embodiments include the power source, communications andtether management in a single hand-carried portable housing. Theportable housing can also include an integrated launch and landingplatform that can be mounted on a vehicle. Such a control stationhousing can comprise a hand carried system having a weight of less than28 kg (or about 60 lbs), and preferably less than 25 kg, and morepreferably less than 22 kg. For mobile operations using ground vehiclesit is preferred to have the ability to dispense and retrieve the tetherto accommodate higher rates of travel. The aerial vehicle can alsodetach from the tether while tracking the vehicle from which it waslaunched and then automatically land the vehicle while it moves.

A further embodiment provides a thermal management system for the basestation portable housing. As the operating voltage of the controlelectronics in the portable housing can cause heating of the system andadversely affect the transmission of power and communication to theaerial vehicle with the tether, the system is cooled by fluid (air) flowwithin the housing. A thermal barrier or heat sink can also be used tovent heat away from the temperature sensitive system components. A metalplate can be used to mount the tether retainer, such as a spool, on oneside and the control electronics can be mounted on a second side.

Some “free-flying” aerial vehicles are powered by a battery andcommunicate wirelessly with one or more ground-based stations. As notedabove “tethered” aerial vehicles are powered by a lightweight filamentextending between the aerial vehicle and a ground station withcommunication between the ground station and the aerial vehicleoccurring over the filament. Rather than transmit network traffic over atwisted pair filament, or in tandem with such transmission, a wirelessRF transmitter/radio connects from the ground station to a RF receiveron the air vehicle. These radios can be connected via hardware andsoftware to the flight network. Alternatively, the system can provide aplurality of communication modes simultaneously such as by wire, opticalfiber, and/or wireless formats as needed for specific payloadconfiguration and application.

Some users have multiple needs with some of their needs best implementedusing free-flying aerial vehicles and others have their needs bestaddressed by tethered aerial vehicles. Due to practical limitations(e.g., budgetary restrictions) users generally cannot have both types ofaerial vehicles. Thus, there is a need for an adaptable aerial vehiclesystem that can fly both under remote power with a tether and as afree-flyer, under battery power.

In a general aspect, a modular aerial vehicle system allows for simple,modular switching between a number of different configurations,including a free-flying, battery powered configuration and a tetheredconfiguration. The aerial vehicle can include an onboard controlintegrated circuit that enables a user to select operating parametersfor different payload configurations, and different communication andpower utilization configuration to configure aerial vehicle fordifferent tasks. The user can open windows available on a OCU displaygraphical interface in which pull down menus allow selection of presetsfor different operating modes. The ground station parameters can alsohave presets corresponding to these modes.

In some aspects, an aerial vehicle having a plurality of rotors, whereineach rotor is tilted to have a different thrust vector than theremaining plurality of rotors, includes a receptacle or “module bay” inits fuselage for receiving modules for configuring the aerial vehicle.One example of a module that can be received by the module bay is abattery power configuration module for configuring the aerial vehicleinto a battery operated mode. In some examples, the battery powerconfiguration module includes a battery (e.g., a lithium ion battery)and circuitry associated with battery power management. In someexamples, the battery power configuration module includes terminals thatcorrespond to terminals located in the module bay such that, when thebattery power configuration module is inserted into the module bay, theterminals of the battery power configuration module are in contact withthe terminals in the module bay (e.g., for power transfer).

Another example of a module that can be received in the module bay is atethered configuration module. The tethered configuration moduleincludes or is attachable to a lightweight tether for connection to acontrol or ground station, data linkage connectors which enable use ofthe tether as both the power conduit, and conveyance mechanism forcommand and control communications and telemetry return, for vehiclesequipped to enable hardwired interface with their ground-based operator.In some examples, the tethered configuration module supplies powerinformation to the user via established vehicle health monitoringstrategies, such that continuous feed of power from the ground isproperly reported, and any battery life-related behaviors (like land onlow power) are precluded.

In some examples, the tether is spooled (e.g., deployed from and/orre-wound) in a body of the tethered configuration module. In otherexamples, spooling of the tether occurs at a ground station, on a waterraft or a ground vehicle. In other applications, the tether can bestatic to provide power to a cellular tower radio transmission system,including power amplifiers and remote radio heads, and can optionallyinclude backhaul of cellular voice and data to a cell tower basestation.

In some examples, the tethered configuration module includes terminalsthat correspond to terminals located in the module bay such that, whenthe tethered configuration module is inserted into the module bay, theterminals of the tethered configuration module are in contact with theterminals in the module bay (e.g., for power transfer, command andcontrol information transfer, sensor information transfer, etc.).

In some examples, a multi-use module is a hybrid tethered configurationmodule and battery power configuration module (i.e., a module includingboth tether hardware and a battery). When in use as a free flyingvehicle, the tether is disconnected from the multi-use module (leavingthe tether management hardware intact), and a battery unit installed inthe multi-use module. When being used in a tethered configuration, thebattery unit is removed from the multi-use module, and the tether isattached. In some examples, the multi-use module is used with both thebattery unit installed and the tether attached. In such examples,circuitry for intelligently switching between battery power andtether-based power is included in the multi-use module.

In some examples, the aerial vehicle includes minimal or no powerconversion, telemetry, vehicle command and control, sensor, orcommunications circuitry. That is, the aerial vehicle includes only afuselage, including spars with thrust generators disposed at their endsand terminals for connecting the thrust generators to an electronicsmodule in the module bay. The electronics module may include a computingcircuitry (e.g., a processor, memory) and/or discrete circuitry forpower conversion, telemetry, vehicle command and control, andcommunications. The electronics module can be swapped in and out of oneor more aerial vehicles.

In some examples, different modules can include different sensor suitesto adapt the aerial vehicle to its mission. Thus, different camerasystems can be used depending upon whether a tether is used or not.

In general, all of the modules that can be received by the module bay,including the tethered configuration module, the battery power module,and the electronics module have the same form factor, and fit withoutadditional modification, into the module bay of the aerial vehicle.

In some examples, modules can be designed to retrofit pre-existingaerial vehicles. For example, a tethered configuration module may beconfigured to fit into a bay or attach to standard attachment points ofa pre-existing aerial vehicle and to provide tethered power to theaerial vehicle. In some examples, such a tethered configuration moduleincludes an RF transponder for receiving command and control informationfrom a ground station via the tether and transmitting RF command andcontrol information to the pre-existing aerial vehicle. The tetheredconfiguration module may also include power conversion and conditioningcircuitry for converting and conditioning the power received over thetether into a form that is usable by the aerial vehicle.

In some examples, the modular aerial vehicle system includes a groundstation including one or more of a generator for generating power, abase station for conversion of the power from the generator fortransmission over the tether and for communicating over the tether, anda spooler for managing an amount of deployed tether.

In some examples, one or more elements of the control station isattached to a moving vehicle such as a commercial vehicle, constructionequipment, military equipment and vehicles, boats and personal vehicles.Power can be provided by a mobile generator or vehicle mounted battery.

Switching between battery powered operation and tethered operation is asimple modular switching operation. System flexibility is increased.Functionality and data capture capabilities are increased. Both theadvantages of tethered systems (e.g., persistent, secure communications,flight duration unconstrained by on-board battery energy capacity) andfree flying systems (e.g., wide range of motion, unconstrained by tetherlength) are achieved in a single system.

In an embodiment, the UAV may be equipped with one or more antennas andfunction as a mobile cell tower. The UAV includes receiver andtransmission electronics to support a cellular communication network inwhich handheld mobile communication devices such as cell phones, tabletsor other internet enabled wireless communication devices can used withthe UAV to connect to the cellular network. An optical transceiver onthe UAV provides for transmission and reception of voice, data andstreaming video using optical fiber(s) in the tether.

In some embodiments, the UAV includes a control and/or communicationssystems chip for the spooler and the base station. The control and/orcommunications systems chip is a single chip solution for networkedpowerline and networked communication applications. In an exemplaryembodiment, the chip is a single chip HD-PLC Powerline Communications(HD-PLC) IC by MegaChips in San Jose, Calif. The chip provides a smallform factor, high performance, low power, robust communications, superbnoise immunity, and high quality of service (QoS) over both AC and DCpower lines. The aerial vehicle can also include the same or similarlyconfigured control and communication chip package to manage both payloadand UAV flight operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in, and constitute apart of this specification, illustrate one or more embodiments of theinvention and, together with the description, help to explain theinvention. In the drawings:

FIG. 1 depicts an exemplary PARC system in an embodiment;

FIG. 2 depicts communication and power connections in an exemplary PARCsystem in an embodiment;

FIGS. 3A-3C depict views of an exemplary aerial vehicle in anembodiment;

FIGS. 4A-4D depict views of an exemplary spooler in an embodiment;

FIGS. 5A-5B depicts an exemplary base station in an embodiment;

FIG. 6 depicts an exemplary DPA/MC in an embodiment;

FIG. 7 depicts an exemplary operating environment suitable forpracticing an embodiment;

FIGS. 8-11B depict exemplary charts used to determine AGL flightrestrictions;

FIGS. 12A-12G illustrates a spooling apparatus is configured to deployand (optionally) re-spool tether for an unmanned aerial vehicle (UAV)such that a tension on the tether is maintained at a substantiallyconstant, desired tension value;

FIGS. 13A-13U illustrates a high-performance (HiPer) spooler apparatusand a modular tether system for a UAV;

FIG. 14A illustrates an exemplary process sequence for operatingnetworked UAV systems in an embodiment;

FIGS. 14B-14T illustrates additional embodiments for UAV operation;

FIGS. 15A-15H, 15IA-15IC, 15J-15O, 15P1-15P2, and 15Q-15U depictexemplary PARC systems;

FIG. 16 illustrates a generator used to provide power to a base stationand tether management system;

FIG. 17A depicts a schematic diagram of exemplary system circuitryincluding both high and low power Y-Board buses in an embodiment;

FIG. 17B is a schematic diagram of an exemplary low power Y-Board in anembodiment;

FIG. 18 is a diagram of an electronics and control schematic blockdiagram in an exemplary aerial vehicle 10 in an embodiment;

FIG. 19A is an exemplary PARC system deploying a UAV as a cell tower;

FIG. 19B is an exemplary PARC system deploying multiples UAVs as celltowers in a networked environment;

FIG. 19C is an exemplary control system for a UAV operating as a celltower;

FIG. 19D is a cross-sectional view of a tether, including wire andoptical fiber;

FIG. 19E is a cross sectional view of a wire pair for a tether;

FIG. 19F is a cross sectional view of a wire pair for a tether thatincludes a strength member;

FIG. 20 depicts a block diagram of exemplary interfaces that may beemployed by an embodiment;

FIG. 21 depicts the use of exemplary operation modes that may beemployed by an embodiment;

FIG. 22 depicts the use of additional exemplary operation modes that maybe employed by an embodiment;

FIG. 23 depicts IQ data being carried in CPRI Bit Streams that aremapped to Ethernet frames via a Mapping Function in an exemplaryembodiment;

FIG. 24A depicts link bonding in an exemplary embodiment;

FIG. 24B depicts an exemplary embodiment providing a communication linkthat utilizes CPSFK modulation;

FIG. 25A depicts a system that includes a base station transmittingpower, control, and/or communication signals through a tether to anelevated transceiver module;

FIGS. 25B-25C depicts an embodiment of an exemplary base station;

FIG. 25D is an embodiment of an exemplary circular cable bundle;

FIG. 25E is an embodiment of an exemplary flat cable bundle;

FIGS. 25F-2511 are embodiments of a system for enabling a UAV for radiotransmission and reception of cellular communication or as an internetportal;

FIG. 25I is an alternate embodiment of a system for enabling a UAV forradio transmission and reception of cellular communication or as aninternet portal;

FIG. 25J illustrates safety interlocks configured to shut down powerunder predefined conditions;

FIGS. 26A and 26B depict block diagrams of an exemplary control system;

FIG. 27 depicts a block diagram of an exemplary a multi-rotor helicopteroperating in the presence of a prevailing wind;

FIG. 28 depicts an exemplary multi-rotor helicopter rotating withoutchanging its position;

FIG. 29 illustrates a modular system for tetherless flight operation;

FIG. 30 illustrates a modular assembly including a module for tetheredoperation;

FIG. 31A-31C illustrates a tether strobe beacon for a UAV; and

FIG. 32 illustrates a process flow diagram of a networked system usingboth tethered and untethered UAVs.

DETAILED DESCRIPTION

Embodiments provide a Persistent Aerial Reconnaissance and Communication(PARC) System that offer extended flight time for a UAV or other aerialvehicle through the use of microfilament, a pair of threadlike wiresthat may transmit over a kilowatt of power to the UAV while alsoenabling transmission of bi-directional data and high-definition video.The PARC system may be rapidly deployed as a low-maintenance unmannedaerial vehicle that allows cameras, radios or other payloads to remainin operation for long durations. The PARC system is designed to beintuitively simple to launch/land and the small logistics footprint maymake the system appropriate for austere environments. The PARC systemmay require minimal training for operations and maintenance. The systemis designed for quick and simplified deployment to minimize operatormanagement while maximizing capability provided in terms ofcommunications extension, force protection, persistent stare, andtactical intelligence.

FIG. 1 depicts an exemplary PARC system in an embodiment. The systemincludes an aerial vehicle 10 equipped with a payload 11, a spooler 20,and a base station 30. The system also includes a data platformadapter/media converter (DPA/MC) 40 that is coupled to an operatorcontrol unit (OCU) 50. Aerial vehicle 10 may be an unmanned aerialvehicle (UAV) or other flight capable robot. The payload 11 may be acamera, radar or another type of surveillance, communication or othersensor required by an end user of the PARC system. The spooler 20 is aground based component that includes a spool assembly that houses thetether spool assembly, a cylindrical hub that holds a pre-wound amountof micro-filament tether to be attached to the aerial vehicle 10. Forexample, in one embodiment, the spool assembly may hold 167.6 meters(550 feet) of micro-filament tether. In one embodiment, themicro-filament tether may be Kevlar-jacketed twisted copper pair withinsulation that provides both a power link and a communication linkbetween the spooler 20 and the aerial vehicle 10. The base station 30 isconnected to the spooler 20. The base station 30 includes an assemblythat houses an AC power input and high voltage conversion electronics inan environmentally sealed enclosure. The base station 30 also includes ahigh voltage output port to supply high voltage to the spooler 20 whichdelivers the high voltage via the microfilament to the aerial vehicle10. A data platform adapter/media converter (DPA/MC) 40 may serve thefunction of connecting an operator control unit (OCU) 50 to the basestation while also providing electrical shock hazard isolation. TheDPA/MC 40 may include an optical port to connect to the base station viaa fiber optic cable and may also include an Ethernet port to connect tothe OCU 50. The OCU 50 may be a ruggedized laptop or other computingdevice equipped with and able to execute the OCU application describedfurther herein enabling control of the aerial vehicle 10. Furtherdetails regarding the operation of tethered and untethered vehicles canbe found in U.S. Pat. Nos. 7,510,142 and 7,631,834, the entire contentsof these patents being incorporated herein by reference.

FIG. 2 provides an alternate view of an exemplary PARC system depictingcommunication and power connections in an embodiment. Base station 30converts power to HV power and provides HV power to the spooler 20. Thebase station 30 also provides a communication link over Ethernet and lowvoltage power to the spooler 20. The spooler 20 provides the HV powerover the microfilament tether to the aerial vehicle 10 for use forenergy intensive operations such as radar sensing and propulsion duringflight operations. As noted above, the microfilament may also provide acommunication pathway used to communicate with the aerial vehicle 10 bythe operator of the OCU 50. The DPA/MC 40 may communicate with the basestation 30 over an optic fiber and communicate with the OCU 50 over anEthernet connection.

In one embodiment, the aerial vehicle 10 may include a number ofcomponents and features such as those illustrated in FIGS. 3A-3C. Forexample, the aerial vehicle 10 may include an aerial vehicle bodyassembly 301, a payload 11, a GPS/Sensor connector 302 and a GPS/Sensortower 303. The aerial vehicle body assembly 301 may house a tetherinterface, system electronics, and a flight control system in anenvironmentally sealed enclosure. The GPS/Sensor connector 302 mayprovide a connector interface to the GPS/Sensor tower 303 The GPS/Sensortower 303 may house, without limitation, a GPS sensor, a pressuresensor, and a digital compass. The GPS/Sensor tower 303 may also includea quick release interface between the GPS tower 303 and aerial vehicle10.

The aerial vehicle 10 also includes, in one embodiment, six strutassemblies 311 and an associated six propeller assemblies 312 The strutassemblies 311 may house the motor, motor electronics and interfaceswith the aerial vehicle electronics in an environmentally sealedenclosure. The strut assemblies 311 may include an integral positivelocking retention collar/nut. The propeller assemblies 312 may be formedas a carbon-fiber rotor that provides lift. The propeller assemblies 312may include propellers configured to turn clockwise and other propellersconfigured to turn counterclockwise. The associated strut assemblies 311may be designed to work only with a specific propeller direction. An LEDassembly 313 may incorporate visible and near IR LEDs in each strut forvisibility. The aerial vehicle 10 may also include a landing gear legassembly 317 composed of carbon fiber tubes that attach to each strutassembly 311 In one embodiment the carbon fiber tubes may attach viasnap on interface and/or be secured by retention clips.

Additional components may also be included in the aerial vehicle 10. Forexample, as shown in FIG. 3B, in one embodiment, the aerial vehicle 10may include one or more batteries in a battery pack assembly 314 Forexample, the battery pack assembly 314 may include one LiPo battery packthat provides power to the aerial vehicle 10 during a pre-launch set-upprocess and that may serve as auxiliary (reserve) power enabling theaerial vehicle to land in the event of power loss/interruption in thepower being supplied via the micro-filament. The battery pack assembly314 may include an integral power leads/connector and battery chargerleads/connector. A second battery pack on the aerial vehicle may serveas a spare battery pack.

The aerial vehicle 10 may also optionally include, in one embodiment, aparachute recovery system canister 316 and a parachute payload port 310.The parachute recovery system canister 316 is configured as an optionalcatastrophic failure mitigation device that is installed on aparachute-specific payload interface plate. The parachute recoverysystem canister 316 may contain a pre-packed parachute and may beattached by four quick-release mounting points to the payload plate. Onecanister may be provided with the optional parachute system. Undercertain circumstances involving a sudden loss of high voltage powerduring operation, the aerial vehicle 10 may be configured toautomatically deploy the parachute from the parachute recovery systemcanister 316 if the aerial vehicle 10 is operating above a pre-specifiedheight threshold. For example, in one embodiment, the pre-specifiedheight threshold may only deploy the parachute if the loss of poweroccurs while the aerial vehicle 10 is above an altitude of 31 meters/102feet. It will be appreciated that other pre-specified height thresholdsmay also be designated in other embodiments. The parachute payload port310 may provide a connector interface for a parachute canistercable/plug. In another embodiment, the aerial vehicle 10 may include oneor more additional parachute canisters that provide additionalprotection in the case of catastrophic failure.

Additional components for the aerial vehicle 10 may include a payloadinterface assembly 315 that provides a secure mechanical mount forattaching payloads to the aerial vehicle body and for providing a strainrelief attachment point for the microfilament connector/tether on a “U”shaped hoop. The aerial vehicle 10 may also include an on/off switch 304that turns power to the aerial vehicle body on/off and activates abattery balancing function.

As shown in FIG. 3C, the aerial vehicle 10 may include a batterycompartment 307 that provides an enclosure for installation andretention of the battery pack assembly and a battery lid assembly 308that provides an environmental seal for the battery compartment. Thesystem may include power management features such as those described inmore detail below and in U.S. application 62/315,873 filed on Mar. 31,2016, the entire contents of which is incorporated herein by referencein its entirety

In one embodiment a micro-filament receptacle 306 is provided on theaerial vehicle 10 that serves as a connector interface for themicrofilament spool housed in the spooler 20.

In an embodiment, a payload 1 1 may be secured to the aerial vehicle 10by means of payload interface mounting studs 309 that provide a rigidmounting interface for the payload. As noted previously, the payload 11may be an imaging device, radar or other sensor used to acquire data.The aerial vehicle 10 may include one or more payload ports 305 thatprovide power, such as 12 VDC power to the payload 11 as well asEthernet based communication.

In one embodiment, the spooler 20 may include a number of components andfeatures such as those illustrated in FIGS. 4A-4C. A spooler enclosureassembly 401 may house the tether spool assembly, a tethertensioning/winding mechanism and control electronics in anenvironmentally sealed enclosure. High voltage power and communicationsconnection ports, and a tether retract button may be located in a rearpanel. A GPS assembly 401 A may provide, without limitation, groundbased GPS, pressure, and a digital compass sensor reference between theaerial vehicle 10 and the spooler 20. Carrying handles 401B may provideergonomic hand grips for lifting or carrying the spooler 20 and coolingfans 401C may provide cooling and directed airflow for the spoolassembly 403. The spooler 20 may also include a high voltage input port40 ID that receives high voltage input (via the base station to spoolercable assembly) for distribution to the spool assembly 403 and aerialvehicle 10. A spool retract button 401E may be configured to respond toa momentary press by retracting the tether upon completion of mission. Acontinuous press or hold of the retract button may retract the tether.An I/O (Data/Power) port 40 IF may receive power (low voltage) andcommunication (via the base station to spooler cable assembly) fordistribution to the spooler 20 and aerial vehicle 10. A cover/lid latch401G may provide a tool-less latch that secures the spooler cover/lidassembly 402 to the spooler enclosure assembly 401. Rubber feet mayprovide a rubber foot/bumper that keeps the spooler from sittingdirectly on the ground and help to dissipate static charge.

A micro-filament intake horn 401J may be provided that is configured toprovide large debris rejection and a non-abrasive, fluted circularopening for the tether during operation. A spooler cover/lid assembly402 may cover the tether spool assembly and tether tensioning/windingmechanism during operation. The cover/lid may be opened during spoolassembly installation and during cleaning/maintenance. A latch tab 402Amay interface with the latch to secure the spooler cover/lid assembly402 to the spooler enclosure assembly 401. A cover/lid hinge may allowthe cover/lid assembly to open/close in a controlled manner.

The spool assembly 403 may house the microfilament intake 401J, as wellas tensioning and level winding electro-mechanical components. The spoolassembly 403 may provide a mounting interface for the spool assembly andguide rollers for secure routing of the microfilament. In oneembodiment, themicro-filament intake/winding assembly 401J mayincorporate guide rollers (×4), pigtail (×1), level winding rollers(×2), retention clip (×1), and tensioning dancer (×1) for management ofthe microfilament during flight operations and post mission retraction.In an embodiment, a high voltage output connector 403B may provide amilitary standard (MIL-SPEC) bayonet style connector interface to thespool connector/plug. In one embodiment, a spool lock ring that is atool-less, quarter-turn locking ring may secure the spool assembly to aspool drive shaft. As noted above, a spool assembly 403 provides acylindrical hub that holds the pre-wound length of tether. The assemblymay include a strain relief clip assembly and a connector plug forattachment to the payload interface plate assembly and a tether port onthe aerial vehicle. In one embodiment, a strain relief 404A may be ratedfor 50 lbs of load and may attach to the payload interface plateassembly titanium hoop. A strain relief clip 404B may attach the strainrelief to the payload interface plate assembly titanium hoop. In anembodiment, an aerial vehicle connector/plug 404C may be provided as aquarter-turn bayonet style connector that mates to the tether port onthe aerial vehicle 10 and a micro-filament tether 404D as previouslydiscussed may be provided in the form of a Kevlar-jacketed twisted paircopper with insulation so as to provide both a power and communicationlink between the spooler 20 and the aerial vehicle 10. A spoolconnector/plug 404E may be provided as a quarter-turn MIL-SPEC bayonetstyle connector that mates to the high voltage connector in the spoolassembly compartment.

Additionally, the spooler 20 may include a base station to spooler cableassembly 405 that may supply high voltage to the PARC spooler 20 andaerial vehicle 10. The base station to spooler cable assembly 405 maysupply power (low voltage to the spooler 20) and communication to thespooler 20 and aerial vehicle 10. The cable assembly may containMIL-rated circular connectors. A brush box assembly 406 may be providedto clean the tether as it passes through and to dissipate anyaccumulated static charge.

FIG. 4D is an illustration for adding an optical fiber cable 1402 to atether deployment device 1404. A filament 1406 providing power extendsthrough a slip ring 1408 and a rotating spindle 1410 into a coupling1412 attached to a side of the spool 1404. In an exemplary embodiment,the filament 1406 is composed of copper. The fiber optic cable 1402 isinserted through a fiber optic rotary joint (FORJ) 1414 into theopposite side of the coupling 1412. In an exemplary embodiment, thefiber optic cable 1402 is approximately 800 microns in diameter but canhave a diameter in a range of 500-2000 microns depending on applicationrequirements. The coupling 1412 serves to connect the filament(s) 1406and fiber optic cable 1402 into a twisted pair within an externaljacket. The external jacket includes a Kevlar layer located inside theexternal jacket but outside the twisted pair. The external jacket(including the Kevlar layer, the fiber optic cable and the copperfilament) serves as a tether providing data communications and power toan UAV. The tether extends from the coupling, wrapping around a spool,and connecting to the UAV.

In some embodiments, the fiber optic cable 1402 is an OFS Micro-LinksAvionics fiber optic cable compatible with connectors and/or terminidesigned for tight jacket construction cables (e.g. ST, Tight Jacket LC,Tight Jacket SC, MIL-29504 pin and socket, Tight Jacket ARINC 801).

A hybrid filament can provide power and/or communications on a copperpair and transmit data and/or communications via the fiber optic linkbetween the ground component(s) and an air vehicle. Some payloads, suchas a high definition camera or software defined radio, may cause thedownlink data rate from the UAV to the ground to be significantly largerthan the uplink data from the ground to the UAV. If an optical fiber isavailable, the high-bandwidth payload communications is shifted to thefiber. The copper communications can continue to be used for air vehiclecontrol and telemetry. As different payloads are installed on the UAV orthe payloads are configured to change the data rate, a communicationscontrol integrated circuit (such as the Megachips system describedherein) module dynamically adjusts the communications link. Securewireless communication can also be used.

In one embodiment, the base station 30 may include a number ofcomponents and features such as those illustrated in FIGS. 5A-5B. Forexample, the base station 30 may include a base station enclosureassembly 501. The base station enclosure assembly 501 may house an ACpower input and high voltage conversion electronics in anenvironmentally sealed enclosure. Power and communications connectionports, and AC input switches may be located in the rear panel. Highvoltage enable/disable controls and status indicators may be located inthe top panel. A magnetic mount 501A may be used by the base station 30to provide a magnetic feature for securing an optional beacon assemblyto the base station 30. A beacon I/O port 501B may provide a connectorinterface to the optional high voltage beacon assembly. In oneembodiment, a rubber sealing cap may be provided for the port when thebeacon is not present. The base station 30 may be equipped with an HVprimer indicator LED 501C and an HV primer button 501D. The HV primerindicator LED 501C may be a colored LED such as a red LED that indicatesthat high voltage is primed. The HV primer button 501D may be providedto enable/disable the high voltage output from the base station 30 tothe spooler 20 and aerial vehicle 10. As a non-limiting example, the HVprimer button 501D may be configured so that a user pressing the buttonfor >4 seconds enables or disables OCU control of the high voltage (itwill be appreciated that the button should not be used during flightoperation of the aerial vehicle 10). An emergency ESTOP switch 501E maybe provided that will immediately terminate power to the PARC System ifdepressed (pressed down) during operation. This button may also serve anarming function (i.e., it enables activation of the HV primer button)during the start-up sequence. In one embodiment, if the ESTOP switch isdepressed upon initial power up of base station 30, the base stationwill not power up. The ESTOP switch 501D may be provided in differentforms including as a two position red mushroom shaped button.

A number of LED indicators may be provided in the base station 30 suchas a High Voltage good indicator LED 501F, an AC good indicator LED 501Gand a fault indicator LED 501H. The High Voltage good indicator LED mayindicate the status of high voltage output (e.g. if not illuminated thehigh voltage is not activated). The AC good indicator LED may indicatethe status of primary and/or secondary AC input from a grid/generatorsource (e.g.: if the LED is not illuminated, AC input is not activated).The fault indicator LED may indicate a system power fault condition(e.g.: if the LED is illuminated, high voltage is automaticallydisabled).

The base station 30 may also include a number of ports, terminals andswitches. These may include an HV output port 501I, a GND lug/terminal501J, a spooler interface port 501K, an Ethernet I/O port 501L, anOptical Ethernet I/O port 501M, a primary AC input port 501N, asecondary AC input port 501O, an aux ac out output port 501P, a primaryAC switch 501 Q, a secondary AC switch 501R and an Aux AC out switch501S. The HV output port may supply high voltage (via the base station30) to the spooler cable assembly to the spooler 20 and aerial vehicle10. The GND lug/terminal may provide an attachment point for systemelectrical grounding. The spooler interface port may supply power (lowvoltage to the spooler 20) and communication (via the base station 30 tothe spooler cable assembly) to the spooler 20 and aerial vehicle 10. TheEthernet I/O port may provide a connector interface to the OCU 50 orrouter/switch and may be used for debug or lab operations. The EthernetI/O port may include MIL-rated connector plugs attached via lanyard. Thebase station 30 may also include an Optical Ethernet I/O port thatprovides a connector interface to Ethernet-fiber converter and fiberoptic spool. This port may be used for connection during normaloperation. Optical Ethernet I/O port may include MIL-rated connectorplugs attached via lanyard. The primary AC input port that provides aconnector interface to a primary AC input source. The primary AC inputport may include rated connector plugs attached via lanyard. Thesecondary AC input port may provide a connector interface to a secondaryAC input source. The secondary AC input port may include rated connectorplugs attached via lanyard. The aux AC out output port may provide aconnector interface to power peripheral device (i.e., OCU). This portmay include MIL rated connector plugs attached via lanyard. It should benoted that voltage available from AUX AC may be the same as voltage onthe Primary AC/Secondary AC. A primary AC switch may be provided as atwo position toggle switch that turns AC input on and off. The secondaryAC switch may also be provided that turns AC input on and off.Similarly, the Aux AC out switch may be provided in the base station 30as a two position toggle switch that turns aux AC output on and off.

The base station 30 may also include heat sinks and/or fins 501T andcooling fans 502A. The heat sinks and fins may provide passive coolingof internal electronics and the cooling fans may provide cooling anddirected airflow for the internal electronics.

An exemplary base station 30 may also include a side plate assembly 502to house the cooling fans and heat sink fins that are integral to thebase station enclosure, rubber feet that keep the base station 30 fromsitting directly on the ground (in one exemplary configuration each sideplate may have two feet) and carrying handles providing ergonomic handgrips for lifting or carrying the base station 30. For example, onehandle may be attached to the base station enclosure and one handle maybe attached to the side plate assembly.

The base station 30 may include a high voltage beacon assembly 504configured to provide a visual indication (e.g.: flashing light) that isilluminated when high voltage is activated. The beacon usage is optionaland may be used at the discretion of the operator depending on lightdiscipline considerations. The beacon may incorporate a cable/plug thatinterfaces with a beacon port on the base station enclosure. The beaconmay be retained on the base station enclosure via an integral magnet.

In one embodiment, the base station 30 may be configured to utilize anumber of different types of cables including but not limited to aprimary AC input cable 505, a secondary AC input cable 506, an Ethernetcable 507 and an auxiliary AC output cable 508 As non-limiting examples,the primary AC input cable may be a 3 meter (10 feet) sealed, shieldedcable with an MIL-rated circular connector that interfaces with a gridor generator power source. The secondary AC input cable may be a 3 meter(10 feet) sealed, shielded cable with a MIL-rated circular connector.The secondary AC input cable is optional and interfaces with a grid orgenerator power source. The connector termination may becustomer-specific. The Ethernet cable is an optional 3 meter (10 feet)Ethernet cable with RJ-45. The Ethernet cable provides a connection froma base station Ethernet port to an Ethernet port on a peripheral device(e.g., OCU or router/switch). An optional auxiliary AC output cable maybe utilized which is a 3 meter (10 feet) sealed, shielded cable with aMIL-rated circular connector. This cable may be used to provide power toa peripheral device (e.g., OCU).

The DPA/MC 40 may include a number of components and features such asthose illustrated in FIG. 6. For example, the DPA/MC 40 may include aDPA/MC enclosure assembly 601 that houses electrical and opticalcomponents in an environmentally sealed enclosure. The DPA/MC 40 mayalso include an A/C power input 602 that includes power cable connectsto an A/C source and a power indicator 603 such as an LED that isilluminated when A/C power is supplied. The DPA/MC 40 may furtherinclude an optical port 604 to connect the DPA/MC 40 to the base stationwith a fiber optic cable. A first OCU port 605 may be utilized by theDPA/MC 40 to connect the DPA/MC to the OCU via an RJ-45 standardconnector. A second OCU port 606 may include an optional RJ-45connection to control the payload on the aerial vehicle 10.Additionally, the DPA/MC may include a data platform (WAN) port 607 usedto optionally connect the DPA/MC 40 to a DHCP external network via anRJ-45 connection. An Ethernet cable may be provided to connect the DPAto the OCU 50. In one embodiment, the Ethernet cable is 3 meters long(10 feet).

When present, the DPA/MC 40 provides electrical protection between anoperator using the operator control unit (OCU) and the Base Station. TheMedia Converter converts the fiber optic signal to copper Ethernet forthe OCU. The fiber optic connection provides electrical isolationbetween the Base Station and the OCU. In an alternate embodiment, theOCU is directly connected to the base station and in such an embodiment,the electrical protection provided by the DPA/MC 40 is absent.

The OCU 50 may be a ruggedized laptop or other computing deviceconfigured to execute an OCU application providing primary flightcontrols and status/warning indications required for the PARC systemoperation. PARC control functions can include but are not limited to;START/STOP (propellers), LAUNCH vehicle, LAND vehicle, YAW vehicle, andCMD ALT (change vehicle altitude), enable/disable vehicle LEDs, andenable/disable high voltage.

An exemplary PARC system may be packaged and transported in three (3)reusable transit/storage cases. Transit cases may include customizedfoam inserts to protect equipment during typical transport methods. Eachtransit case may be equipped with integrated wheels to allow for easymovement in flat terrain. In one embodiment, transit cases may serve aswork benches for assembly of the aerial vehicle 10.

FIG. 7 depicts an exemplary operating environment suitable forpracticing an embodiment. More specifically, prior to operation, anoperator of the PARC system may locate the base station approximately 3meters from the spooler 20 while the spooler may be located 5-10 metersfrom the aerial vehicle 10 before launch. The operator may also wish toclear around the aerial vehicle to a diameter of 100 feet and a radiusof 50 feet.

Prior to the aerial vehicle 10 being deployed in the PARC system, theoperator should first determine a safe operating altitude above groundlevel for a given aerial vehicle configuration and the specificatmospheric conditions then present. In one embodiment the operator mayfirst estimate a density altitude (DA) at the intended mission location.As explained further with reference to FIGS. 8-11, the operator mayfollow the following exemplary sequence.

1. Determine the elevation above sea level at the mission location (fromterrain, military map references, etc.).

2. Determine the maximum current/forecast air temperature expectedduring the mission, and the predicted wind velocities (from localweather station, forecast, etc.).

3. Check for special flight conditions or aviation authoritynotifications affecting the intended flight area (Notice to Airmen(NOTAM) bulletins and other sources) about potential hazards orobstacles by consulting:

4. Look up (estimate) the density altitude from the chart presented inFIG. 8.

5. Consult the charts of FIGS. 9 and 10 for guidance on Above GroundLevel (AGL) flight envelope restrictions for the PARC System with andwithout the parachute recovery system installed.

It should be appreciated that the flight envelope is defined not only bydensity altitude but also by wind and temperature. At density altitudesabove 8000 feet flight is allowed by the chart with the parachute onlyif payload is equal or less to 2 lbs (˜910 g) and air temperature is ator below 40° C. Without the parachute a heavier payload of up to 3.6 lbs(˜1650 g) can be flown according to the charts as long as wind speedsare at below 10 knots (11.5 mph) and air temperature is at or below 40°C.

A further example of this preflight atmospheric determination process isnow discussed with reference to FIG. 11. As an explanatory example, fora flight site with an elevation of 1,000 feet, anticipating a maximumtemperature of 85° F. (about 29° C.), the operator locates thetemperature point on the bottom axis of FIG. 8, and follow it up to thehorizontal line representing 1,000 feet in FIG. 11. The operator thenuses the sloping lines to identify the corresponding pressure (akadensity) altitude. The result for this test instance is 3,000 feet, andis shown in the lower half of FIG. 11. Once the result of 3,000 feet DAis determined, that entry is located on the appropriate flight envelopechart. In this example, using the chart for 3.6 lb payload with noparachute installed as shown on FIG. 9, flight is permissible from 15 mup to the 120 m limit. It will be appreciated that the analysis may alsobe programmatically performed by the OCU 50 and a result presented tothe operator following the operator providing initial input parameters.It should also be appreciated that wind conditions for takeoff andlanding should also be accounted for when determining missioncommencement. In one embodiment, an aerial vehicle 10 in the PARC systemcan operate in in continuous winds of up to 25 knots (29 mph). However,in one embodiment, takeoff and landing should not be performed undersustained or gusty surface winds that exceed 15 knots (17.2 mph). Itwill be appreciated that the exact limitations for operation depend onthe particular configuration of the aerial vehicle 10. It should also beappreciated that wind shear is typically present and that as the aerialvehicle 10 increases its AGL, altitude wind speeds will be graduallyincreasing.

An exemplary Power up sequence for the base station 30, spooler 20 andOCU 50 is described below:

1. The OCU 50, base station 30, spooler 20, AC power source(grid/generator), and any ground electrodes are properlyconfigured/connected and positioned.

2. The base station 30, spooler 20, and aerial vehicle 10 are correctlysituated/oriented for flight operation as determined in the sitepreparation instructions.

3. The base station “ESTOP” button is set to the “up” (power enabled)position, prior to setting any of the AC toggle switches to the “ON”position. The base station 30 will spin up the fans and immediately shutoff if the ESTOP button is set to the “down” (power disabled) position.

4. The base station 30 and spooler 20 are powered up by pulling the“PRIMARY AC” toggle switch up to the “ON” position. If the “SECONDARYAC” input is also being used, set the toggle switch to the “ON”position.

5. Set or verify that the “AUX AC” toggle switch is set to the “OFF”position.

6. Perform “ESTOP” test procedure to ensure that it is operatingproperly. Depress button and confirm that the system has powered down.If successful re-set the “ESTOP” button and power the system back up(step 4, above). If the “ESTOP” test fails, the aerial vehicle 10 shouldnot be launched.

7. Boot up the OCU 50 by pressing the power-on button. Upon power-up,the OCU 50 will automatically connect to an appropriate user account andthe operator will be provided an opportunity to launch the OCUapplication providing flight and other controls for the PARC system.

An exemplary power up sequence for the aerial vehicle 10 is describedbelow:

1. After the OCU power-up sequence has completed, the tension on themicrofilament is reduced thus allowing the microfilament to be pulledout freely. Carefully extend the microfilament out to the aerial vehicleby grasping the strain relief clip and pulling the microfilament out tothe aerial vehicle location with approximately 1 meter (3 feet) ofslack.

2. Connect the spool strain relief clip to the bottom of the U-shapedhoop on the payload interface plate.

3. Ensure that the spool strain relief clip is properly secured to thehoop.

4. Connect the microfilament connector plug to the aerial vehicle powerport by aligning the plug keying feature with the aerial vehicleconnector port, pushing up to engage the plug, and rotating the plugcollar quarter-turn to lock.

5. Power up the aerial vehicle by toggling the “ON/OFF” switch for >3seconds away from the center position.

6. Clear the area in the immediate vicinity of the aerial vehicle andreturn to the base station 30, spooler 20 and OCU 50 set-up location.

7. Return to the OCU. The OCU application has been sensing and awaitingaerial vehicle initiation, once it recognizes the aerial vehicle. TheOCU loads the user interface.

8. Once the interface is available and HV is primed, enable high voltageby pressing the enable HV button on the screen's bottom menu bar. Nowthe aerial vehicle is being powered via the microfilament. To close theconsole window press the console button.

9. To disable high voltage, use the ‘disable HV button on the interface.It only appears if power is active.

An exemplary launch sequence for the aerial vehicle 10 is describedbelow:

1. Start rotors by pressing the start rotors button in the lower left ofthe screen in the UI provide by the OCU application.

2. The “Start Rotors” button annotation will change to “Starting Rotors”and a progress bar will appear underneath it. Wait for the motors tostart.

3. Continue the pre-launch process, by hitting “GO” button on the UI totake off, or select the red X to abort the takeoff.

4. The flight commences, and the OCU screen updates. On the OCUapplication interface the flight state switches to “Flying” and theactual altitude will be reported in the altitude display. An actionbutton may change to “LAND” and yaw controls become available. Theinterface may also display a flight time clock indicative oftime-in-air. A map may be displayed in a corner of the interface and aGPS position may also be displayed.

The OCU 50 executes an OCU application providing flight controls to anoperator. The flight controls include, but are not limited to, yawcontrols, LED controls, altitude adjustment, and landing controls. Theyaw controls may be needed if a landing leg is interfering with thefield of view of the camera or if motors are overly stressed when theaerial vehicle 10 is flying at high AGL altitudes under continuous windconditions. In the latter scenario, the aerial vehicle 10 may be yawedevery hour (e.g.: yawed 30 degrees) so that load is shared between thestruts. In one embodiment, the yaw controls are presented on theinterface so that the operator looks at the controls with the sameperspective as looking at the aerial vehicle 10 from behind. The LEDcontrols may be located on the ends of the Aerial Vehicle's struts andcan be activated and dimmed as needed. The LEDs may be visible LEDs(i.e. to the naked eye) or infrared LEDs including near infrared LEDs.The LEDs may be manipulated via the interface provided via the OCUapplication. Similarly, the aerial vehicle 10 may have its altitudeadjusted during flight by way of a control on the OCU interface such asa slider or other UI mechanism. The OCU application may also provide aland button or similar UI component that when clicked sends a command toland to the aerial vehicle 10. In one embodiment, pressing a provided“resume” button on the UI provided by the OCU application during thelanding may cause the landing to abort and the aerial vehicle 10 toreturn to its station.

In one embodiment, to address the event of an extreme emergency duringflight in which a precipitous, rapid descent is required, a “forcelanding” button or similar UI component may be provided via the OCUapplication interface. To force a crash landing by increasing thedescent rate to up to 10 meters (33 feet) per second, an operator maypress the force landing button to bring the craft down very quickly.This forced landing button may also be used to terminate propelleraction in the event of a very gentle landing, in which the aerialvehicle's autonomous systems did not detect the landing event, and therotors continue to spin even after the aerial vehicle 10 is on theground.

The OCU 50 allows an operator to access payload controls viaajoystick/gamepad or similar device communicating with the OCUapplication. For example, for camera payload, the controls may includezoom, pan and tilt, and focus controls without limitation. In oneembodiment, the zoom controls may allow an operator to use the triggerbuttons on a joystick, use a zoom slider on the OCU applicationinterface, select an up or down button on a zoom display on the OCUapplication, or use +− buttons on a keyboard for the OCU to zoom in andout. A zoom magnification value may be provided on the OCU applicationUI. In an embodiment, the pan and tilt controls may allow a user to usejoystick buttons to pan and tilt, use pan and tilt buttons on the OCUapplication UI or use arrow buttons on a keyboard for the OCU. A fieldof view indicator value may be provided on the OCU application UI.

In an embodiment the OCU application UI may allow a camera selection bythe operator of the PARC system. For example, the controls may allow anoptical or thermal camera to be selected. If a thermal camera isselected, an additional button indicating flat field correction (FFC)may appear beneath the camera selection buttons and the field of viewindicator may update to correspond to the thermal camera's field ofview. FFC may improve the contrast when using the thermal camera.

In one embodiment, the PARC system also provides advanced controls viathe OCU application UI to control payload operations. As a non-limitingexample, the UI may provide controls for autofocus, focus infinity, anIR cut filter, a defog control and aperture controls. Autofocus placesthe camera in autofocus mode, this frees the operator from manuallyverifying and adjusting focus during use. In one embodiment, thiscontrol can also be invoked by the “Y” yellow button on the joystickcontroller. Focus infinity sets the camera for an infinite target. Thisis primarily used to examine items of interest very far away, whenautofocus cannot establish a lock. In one embodiment, this can beinvoked by the “B” red button on the joystick controller. An IR CutFilter enables and disables the filter, and can improve the low lightsensitivity of the camera. A defog setting can be set to auto or tolow/medium/high, and can improve contrast when observing targets throughobscuring fog, smoke, or haze. Aperture controls set the camera'saperture, adjusting this optimizes performance under various lightingconditions. Additional controls such as “scene lock” which provide astable view of an area under observation and “object track” which allowthe camera to track and follow an object may be provided via the OCUapplication UI, the joystick and/or a combination thereof.

OCU application controls (visible in the UI) may include, withoutlimitation, buttons, sliders, or pull-down menus that may be accessedusing the computer keyboard, touchscreen (if equipped), or mouse.

A multi-node radar UAV network can be used in conjunction with preferreddevices and methods for using UAVs as described generally herein.

Referring to FIGS. 12A-12C, a spooling apparatus 1200 is configured todeploy and (optionally) re-spool tether 1202 for an unmanned aerialvehicle (UAV) such that a tension on the tether 1202 is maintained at asubstantially constant, desired tension value. The spooling apparatusincludes a chassis 1204 with a spool 1206 attached thereto. In general,the spool 1206 is attached to the chassis 1204 in such a way that it isunable to rotate relative to the chassis 1204 (although it should beunderstood that in some alternative embodiments, the spool 1206 may beable to rotate as well). A motor 1208 is disposed in the center of thespool 1206. The driven portion of the motor 1208 is attached to a spring1211 which is in turn attached to a ring bearing 1213. In someembodiments, the motor 1208 is an “outrunner” where the shaft is heldstationary and the housing rotates around it.

An arm 1210 is attached to the ring bearing 1213 such that the arm 1210is coupled to the drive portion of the motor 1208 via the ring bearing1213 and the spring 1211. A pulley 1212 is disposed at the end of thearm 1210 and is configured to receive tether 1202 from the spool 1206.Another pulley 1214 is disposed at the center of the spool 1206 and isconfigured to receive tether 1202 from the pulley 1212.

In some examples, the spool 1206 has larger diameter than in previousapproaches, and is fixed into the chassis 1204 of the spooler. It ismounted horizontally, but could be mounted in different orientations.The motor 1208 is mounted co-axially and internal to the spool 1206. Themotor 1208 is separated from output shaft by gear(s), belt(s), etc.

The pulley 1212 at the end of the arm 1210 is positioned to direct thetether 1202 from the spool 1206 to the center axis of the motor 1208,where is goes around the second pulley 1214 and continues on the motoraxis away from the motor 1208.

As the motor 1208 turns, the tether 1202 is wrapped around the spool1206. At equilibrium, the torque in the motor 1208 is proportional tothe tension in the tether 1202. A motor controller is programmed suchthat the motor 1208 outputs a specific torque under all circumstances.However, in a dynamic situation, where the UAV is accelerating up ordown, the tension deviates due to the angular acceleration of the motorassembly. As the UAV accelerates downward, the tension drops and as theUAV accelerates upward, the tension increases.

In some examples, a buffer (e.g., the spring 1211) is added bydecoupling the rotating arm 1210 from the motor 1208 and allowing thearm 1210 to pivot on the ring bearing concentric to the motor shaft. Thespring 1211 connects the arm 1210 to the motor 1208 such that when atorque is applied to the motor 1208, and is resisted by the arm 1210,the force is transmitted through the spring 1211 and it deflects. Basedon the stiffness of the spring 1211 and the configuration of thebearing, the movement could deflect a small amount, or up to manyrotations. In some examples, the bearing deflects close to onerevolution. This feature achieves an effect analogous to that of thedancer in the previous design. As the UAV is accelerated up or down, thebuffer is able to take up or pay out a length of tether 1202 in order toisolate the high inertia of the motor 1208 from the tether 1202.

In some examples, the tension on the tether 1202 can be inferred basedon a measurement of the deflection in the spring 1211. Tensiondetermination on the dancer in previous designs was a simple matter ofmeasuring the deflection on the arm 1210 with an encoder, potentiometer,or other sensor. In some examples, to measure the deflection of thespring 1211, two encoders are used. The first encoder is connected tothe drive motor 1208, and reports the angular position of the motor 1208with respect to the fixed chassis 1204. The second encoder is mounted onthe rotating arm 1210 assembly, and is able to measure the angularposition of the rotating arm 1210 with respect to the fixed chassis1204. Subtracting one encoder value from the other returns the angularposition of the rotating arm 1210 with respect to the motor 1208, thusproviding the deflection of the spring 1211 and the tension in thetether 1202.

This design meets all tension management requirements and does so usinga very simple layout, requiring a minimum of components. Further, insome examples, this design enables addition of fiber-optic cable to thetether 1202, which can be damaged by the small bend radius inherent inprevious spoolers. The elimination of the high voltage slip ringprovides environmental advantages because mercury is a toxic substanceand its use and disposal are governed by US Federal and internationalregulations.

In at least some examples, operation is controlled by a processorexecuting stored software included with the spooler apparatus. Thesoftware can be stored on a non-transitory machine readable medium andincluding machine language or higher level language instructions thatare processed.

FIGS. 12D-12G illustrate additional embodiment features including arotating pulley (FIG. 12F) at 1220 that winds or unwinds the tetheraround static elements such as a disc or spaced apart posts that serveto retain the tether one device. FIG. 12E has an optional dancer orpinch roller assembly 1223 that can be used to control the load on thetether retention system. Alternatively, as described hereafter, thedancer and pinch roller features are not utilized in embodiments wherethe retaining element or spool is spring mounted.

Pulley elements 1230 can be used to pivot with the tether axis tofacilitate movement through the exit aperture in the housing that can becentered above the tether retaining disc 1235 seen in FIG. 12G.

It is to be understood that the foregoing description is intended toillustrate and not to limit the scope of the invention, which is definedby the scope of the appended claims. Other embodiments are within thescope of the following claims.

FIGS. 13A-13G illustrate a high-performance (HiPer) spooler 1300configured to deploy and re-spool tether for an unmanned aerial vehicle(UAV) such that a tension on the tether is maintained at a substantiallyconstant, desired tension value. FIGS. 13A-13G describe a refinedversion of FIG. 12 that is higher performance than the spooler describedin FIG. 12.

FIGS. 13A-13D illustrate external components of the HiPer spooler 1300.The HiPer spooler 1300 uses a central motorized arm 1302 to wrap atether 1304 around a large diameter, low profile (flat) spool 1306 asthe primary means of managing the tether 1304 during flight operations.As a motor turns, the arm 1302 wraps the tether 1304 around the spool1306. The HiPer spooler 1300 is designed to an increased tether forceand speed capability, enabling faster spooling and an ability to operateon bumpy roads and maritime environments. The HiPer spooler 1300 furthereliminates a need for a high voltage slip ring, which improvesreliability and reduces cost.

The spool 1306 may vary in size depending on the embodiment. A largerspool 1306 has less twisting per length and runs at a lower speed. Inaddition, the cross-section of the tether 1304 on the spool 1306 issmaller, leading to better cooling and better wrapping. In an exemplaryembodiment, the HiPer spooler 1300 is 24×24×12 inches. Thus, the spoolerhousing is preferably less than 120,000 cm in volume. Thus, it isdesirable to utilize an upper rate of deployment and retrieval in arange of 3 to 8 m/s and preferably of 4 to 6 m/s.

One aspect of this design is that the tether 1304 twists one time perrevolution of the spooler arm 1302. When the spool 1306 is initiallywound, the twist will be applied to the tether 1304. As the spooler 1300pays out and the AV ascends, the tether 1304 will go to its naturaluntwisted state. During a landing, the twist will be absorbed back intothe spool 1306. Methods to mitigate the effects of twisting includeadding a stiffening jacket over the top ˜5 meters of tether 1304 andusing an angled roller at the entrance of the spooler to help induce atwist as the tether 1304 is taken up.

In an exemplary embodiment for the HiPer spooler 1300, the maximumtension overload is 4 lbs., the nominal operating minimum is 1 lb., thenominal operating maximum is 3 lbs., the tension set-point tolerance is+/−0.2, the brake tension is 8 lbs., the maximum acceleration is 9.8m/s², and the maximum velocity of retraction is 5 m/s.

In some embodiments, the HiPer spooler 1300 and the base station 1308are combined to form a single unit or enclosure, also known as a groundunit. The HiPer spooler 1300 is designed to integrate with the basestation 1308. At least some components 1305 of the base station 1308 areattached to the base plate 1310 on an opposite side of the spool 1306.The base station 1308 provides high voltage power to the air vehicleconverted from an AC source. Along with DC power, the base station 1308provides a means to send and receive data from the air vehicle to theoperator and interface to the spooler assembly. In additionalembodiments, all heat generation components of the power electronicshave heat sinks mounted directly to the underside of the base plate1310. Additional fan-sinks may be used to internally move heat from theair onto the base plate 1310. The base station 1308 is attached to abase plate 1310.

An upper cover 1312 includes a moveable door 1314. The tether passesthrough a hole 1315 in the upper cover 1312. One of more wire bulkheadsare able to pass through the base plate 1310 to a UT/connector board 1316 on the upper cover 1312. Thus, the UI controls 1316 are on the topsurface and the connectors may be mounted on the side panel 1318, nearthe top.

In some embodiments, the upper cover 1312 serves as a landing platformintegrated onto the top of the ground station 300 to facilitate takeoffand landing. In some embodiments, the landing platform could be in theform of a ring, with a rubber or foam or brush edge to cushion andstabilize the drone on landing. The landing platform may be adjustablein height. The landing platform may also utilize precision landingtechnology, such as using Real Time Kinematic (RTK) GPS, Ultra High Band(UHB) radio beacons, Infrared beacons IR beacons, and/or tethertracking.

When matching the performance improvements of the HiPer spooler 1300versus the spooler described in FIG. 12, the spooler is limited to atether payout and retraction speed of 2.45 meters per second. The HiPerspooler 1300 generally has to payout speeds of 2.8 m/s and retractionspeeds of 3.3 m/s. However, this is not the limit of the capability. TheHiPer spooler 1300 preferably has a speed limit in a range of 4-8 m/s,and at least 7.75 meters per second.

FIG. 13D represents the ground station being placed in a shippingcontainer is a way that allows the ground station to be operated whileremaining in the shipping case.

FIG. 13E illustrates a cooling system for the HiPer spooler 1300. In oneembodiment, the spool 1306 is connected to top of the base plate 1310 bythick, double-sided foam pads. HiPer spooler 1300 includes a fan inlet1320 in the base plate 1310 for taking in air. Blowers direct air into aspace or a gap 1322 in the base plate 1310. Air travels through the gap1322 and up through the ports 1326 into the spool plenum 1328, and outthrough the wrapped filament. The air flows outward radially when theinner plenum is pressurized.

The cooling system is used to cool the filament/tether 1304 on the spool1306, but also moves ambient air across the base plate 1310. This movingair can remove heat added to the base plate 1310 from power electronicsbelow. FIG. 13E further illustrates a volume of space under the baseplate 1310 suitable for mounting electronics. The electronics previouslyhoused in the base station 1308 could be mounted in this space, in a waysuch that a conductive path could be maintained between the heatgenerating components and the base plate 1310. This allows effectivecooling of these components, provided that there is sufficient air flowfrom the blowers above.

In experimental tests, continuous current was passed through filamentand two blowers powered, and filament was allowed to reach steady-statetemperature.

Thermocouples were positioned at various places around the spool. Inevery case, one thermocouple was placed close to the perforated innerwall, another in the middle (radially) of the filament layers, and athird under a few layers of filament towards the outer edge of thefilament stack.

Initial findings after several tests suggest that maximum filamenttemperature did not rise more than ˜77° C., 53° C. above ambient. Thelowest temperature corresponds to the thermocouple closest to theperforated inner wall, while the highest temperature occurs in thethermocouple near the outer edge of the filament stack. Despite theouter thermocouple having a more direct path for heat exit into ambientair, the heated air from the inside of the filament stack tends to warmthe outer region, so the highest temperatures are seen towards the outerwall of the filament.

At 1.7 A continuous current, the temperature rise appears to be withinmaximum allowable parameters; tests were also performed at 1.3 A and 1.5A continuous current to get a sense of temperature rise during more“normal” power utilization. The PARC flies in 60° C. ambienttemperature, including solar loading and with heat ingress into thespool from the electronics below the aluminum baseplate. Therefore,filament temperature rise above ambient should not exceed 60° C. At 1.3A current, observed temperature increases fall below a 65° C. max.Further, the air vehicle is likely to be airborne by the time thesesteady-state maximums are observed, leading to less filament on thespool and decreased temperature maximums. Based on the experiments, thecooling appeared to be adequate in the flat spool design as shown in theHiPer spooler 1300.

FIG. 13F shows an example of electronic boards 1344 attached to theunderside of the base plate 1310, as well as the drive system of thespooler (motor 1336, belt 1338, sprocket 1340 and encoder 13423). As thebase station 1306 into the spooler 1300, the electronic boards 1344 areattached to the base plate 1310 in a way to heat sink the powerdissipating components to the base plate 1310, and that the base plate1310 is cooled by a fan from above.

FIGS. 13G-13I illustrate a tether control system for the HiPer spooler1300. The layout of the system is that there is the arm 1302 attached tothe main spindle 1334. On the main spindle 1334, a timing belt pulley404 is mounted on its own bearings and coupled to the spindle 1334 shaftwith a spiral torsion spring 1338. All of the torque transmitted throughthe pulley 404 and to the shaft travels through the spring 1338. Spiraltorsion springs do not have contact between the coils (unlike helicaltorsion springs) and have a more consistent torque profile. In someexamples, the tension on the tether 1304 can be inferred based on ameasurement of the deflection in the spring 1338.

A motor 1340 drives the pulley 402 with a timing belt, which in turnsmoves the arm 1302. As the motor turns, the tether 1304 is wrappedaround the spool 1306. At equilibrium, the torque in the motor isproportional to the tension in the tether. The motor 1340 has an encoderfor its own control (referred herein as a motor controller). The motorcontroller is programmed such that the motor outputs a specific torqueunder all circumstances. However, in a dynamic situation, where the UAVis accelerating up or down, the tension deviates due to the angularacceleration of the motor assembly. As the UAV accelerates downward, thetension drops and as the UAV accelerates upward, the tension increases.

As shown in FIG. 1311, second encoder 1346 is mounted in unit with thetiming belt pulley and measures the angle between the pulley 404 and thespindle 1334 shaft (or the deflection of the spring 1338). As the springconstant is known, this angle equates to the actual torque transmittedthrough the spring 1338. Because the encoder 1346 is rotating with thepulley 404, a slip ring 1347 is required to connect the encoder to aprocessor.

As shown in FIG. 13I, in an alternate control method, the slip ringcould be eliminated by using an encoder on the end of the spindle 1334shaft, measuring the position of the shaft relative to ground. Todetermine the deflection of the spring 1338, the motor position issubtracted from the spindle 1334 position.

In an exemplary embodiment, the drive train requirements are continuoustorque at 3 lbs. tension, 0.45 nm; Peak motor torque, 0.6 nm; peak motorspeed @ 5 M/s tether speed, 1813 RPM; motor encoder, incrementalquadrature, 1600 cpr (Maxon MILE Encoder 411964); and MotoVoltage 36v.The timing belt tensioning mechanism is of fixed displacement type.

A brake 1342 has been added to the system to prevent the arm 1302 fromrotating when power is off. The primary purpose of this is to preventthe tether 1304 from unwinding and tangling in transport. Secondarily,the brake 1342 can be engaged in an emergency condition in the eventthat the AV is in a runaway condition. In such a case, the requiredtension is the total thrust, minus the AV weight. In some embodiments,the brake is on the output shaft to prevent vibrating of the rotatingarm during shipment.

A hand release is used whenever the arm needs to be moved with poweroff, for example, during loading/unloading the spool 1306, removingslack for transport, or setting up the HiPer spooler 1300. The handrelease will be momentary, with a spring return. Because the brake 1342cannot be left in the unlocked position, a switch is not necessary.Alternatively, a switch could be used to indicate to the control unitthat the brake 1342 has been disengaged.

In at least some examples, operation of the HiPer spooler 1300 iscontrolled by a processor executing stored software included with thespooler apparatus, as described in FIG. 30. The software can be storedon a non-transitory machine readable medium and including machinelanguage or higher level language instructions that are processed.

FIG. 13J illustrates a horizontal view of the spooler arm 1302 and spool1306, including the tether (or filament) 1304, spindle 1334, an innerpulley 1348, and an outer pulley 1350. The outer pulley 1350 is disposedat the end of the arm 1302 and is configured to receive tether 1304 fromthe spool 1306. The inner pulley 1348 is disposed at the center of thespool 1306 and is configured to receive tether 1304 from the outerpulley 1350.

In one embodiment, outside diameter of spool 1306 is 18 in. (457.20 mm),and large diameter of current pulley is 60 mm. Therefore, length of thearm 1302 to center-of-rotation of the outer pulley 110 is approximately258.60 mm. In the above configuration, the center of rotation in thecenter of the outer pulley 110 is 263 mm from the center of rotation ofthe vertical shaft. The angle of the arm 1302 is −7° and the angle ofthe tether 104 is −10°.

The spindle arm 1302, with outer pulley, is able to pivot upward about apoint near the spindle axis in order to provide clearance to theinstallation or removal of a spool 1306 of microfilament tether. In anexemplary embodiment, spindle arm 1302 is attached to the spindle shaft.Three ball-spring plungers in this design are inserted in the piece 32mm from the arm center-of-rotation, offset 120°. A hard stop is builtinto the main support piece to lock the arm 1302 into a −7° pitch, andthe arm 1302 can be rotated clockwise by 60° position. In bothpositions, the arm 1302 position is held in place with 3 detents on thesurface of the main support. In one embodiment, the width of the arm is0.75 in square with a 1/16 in wall thickness.

FIG. 13K illustrates a system block diagram for controlling a spoolersystem. The system includes a microcontroller 1360. In an exemplaryembodiment, the microcontroller 1360 is a PIC32MX795F512L-801/PTmicrocontroller. The microcontroller 1360 is in communication withdevelopment tension and payout assemblies 1362. The development tensionand payout assemblies 1362 include a tension sensor, an encoder, and apayout encoder. In an exemplary embodiment, the tension sensor is aHonigmann RFS 150 sensor. In an exemplary embodiment, the encoder is anIMS22 A50-B28-LS6 Bourns encoder. These can be high resolution sensorsused to qualify the accuracy of other measuring techniques, such as howwell the spring deflection method works to determine tension and thenumber of wraps to determine the amount of tether paid out.

The microcontroller 1360 is further in communication with a motorassembly 1364. In an exemplary embodiment, the motor assembly 1364includes a Maxon 411967, a spindle and a brake. The motor assembly 1364further includes a BLDC motor in communication with a spindle encoder,and temperature sensor. In an exemplary embodiment, the brake is a3-20-4501G-10-EG, the BLDC motor is a Maxon 323772, the spindle encoderis a AS5040, and the encoder is a Maxon 4 11964.

The microcontroller 1360 is further in communication with (a) anoperator control unit (OCU) 1366 via an ethernet 1368 (such as an I-TempBeagle Bone BB-BBLK-000-ITEMP 710), (b) a power source 1370, (c) a fan1372, and (d) a jog button 1374 that, when pressed, retracts thefilament. In an exemplary embodiment, the power source 1370 ispreferably 36-48 VDC. In an exemplary embodiment, the fan 1372 is 12VBFB1212VH-TA50 17.6 W.

The microcontroller 1360 is further in communication with a brake engageswitch 1376 via a MODFET switch board 1378.

FIG. 13L illustrates a control system for a ground station, such asground station 300, that combines the functions of a base station and aspooler into one component. The ground station provides control andspooling of the filament, as well as house the HV power andcommunication to the air vehicle. The OCU connects to the ground stationvia fiber or Ethernet. In some embodiments, the DPA functionality iswrapped into the ground station, while the Media Converter functionalitywill remain at the operator's location.

The control system includes a central processing unit (CPU) 1380 incommunication with an indicators and user control component 1381. Theindicators and user control component 1381 transmits user UAV controlinstructions to the CPU 1380 and receives indicators (e.g., AC power on,fault indicators, HV on, etc.) from the CPU 1380.

The CPU 1380 is in further communication with an external ground sensorsystem 1382. The external ground sensor system 1382 transmits data fromsensors located on the ground, including on a mobile vehicle (e.g., caror boat) to the CPU 1380. The data may be used by the system forprecision takeoff and/or landing. For example, the data may indicate alocation and an angle of a landing platform.

The CPU 1380 is in further communication with an OCU 1383 via a copperor fiber Ethernet. The OCU 1383 transmits commands to the CPU 1380 andreceives data from the CPU 1380.

The CPU 1380 is in further communication with an air vehiclecommunications component 1384. For example, the air vehiclecommunications component 1384 may transmit video and/or sensor data tothe CPU 1380. In an exemplary embodiment, the communications isperformed through a microfilament. The air vehicle communicationscomponent 1384 communicates with a HV/communications fusion 1392.

The CPU 1380 is in further communication with a spooler controlcomponent 1385. The spooler control component 1385 controls thespooling, unspooling, and tether tension of the tether based on amovement (e.g., ascending, descending, etc.) of the UAV and tethertension. The spooler control component 1385 communicates with a motorcontrol component 1386 that controls a motor for rotating a spooler armto spool and unspool the tether (tether management 1387). The spoolercontrol component 1385 may control the tension of the tether byinstructing the motor control component 1386 to turn the motor. Spoolersensors 1388 receive data based on the tether management 1387 andtransmits the data to the spooler control component 1385 for furtherspooler control.

An AC input filtering and condition component 1389 transmits power to anAC to low voltage DC system power 1390 and DC to HV-DC 1391. The DC toHV-DC 1391 transmits power to the HV/Communications fusion component1392.

A preferred embodiment of the invention relates to systems and methodsof operating a radar device mounted on one or more UAVs to monitor anairspace for static objects on the ground, other moving objects and/orairborne vehicles. A tethered UAV system in which power is supplied tothe UAV using the tether has particular advantages for UAV mounted radarsystem operation. This enables persistent operation of the radar systemduring flight of the UAV for days or weeks of operation which is notpossible for battery powered autonomous UAVs.

A plurality of UAVs, each with a radar system mounted thereon, canperform coordinated monitoring of a three dimensional airspace, forexample. Such a multi-node UAV radar system can be operated by a singleintegrated control system, or control can be distributed among two ormore control systems in communication with each other. Ranges, velocityclassification, and identification information generated by each UAVmounted radar assembly can be partially processed on board each UAV by aprocessor mounted thereon. The raw or processed data generated by theUAV radar assembly can be transmitted to a ground based processingsystem using the tether or by wireless transmission.

FIG. 13M illustrates a tether control feedback loop to control aposition of a moveable arm that deploys tether from a tether retainerduring flight of a UAV, in accordance with an exemplary embodiment. Thetether mechanism includes a tether controller and a microcontroller,such as a Renesas R7. Steps 200-218 illustrate the control feedback loopoperations that are performed using the microcontroller. At step 200, anencoder value is obtained from a position of the moveable arm (alsoknown as a dancer arm) that deploys the tether. At step 202, the encodervalue is converted to radians. At step 204, readings from the moveablearm are filtered. At step 206, a filtered arm position value is passedto an arm position control loop. At step 208, the arm position controlloop receives the filtered arm position as input. The microcontrolleruses the arm position control loop to compare an actual position of themoveable arm to a commanded position. The commanded arm position isdetermined by a commanded tension value. The arm position control loopoutputs a commanded velocity for the motor. At step 210, a value fromthe motor encoder is obtained and an actual velocity of the motor inrad/s is determined. At step 212, a velocity control loop receives thecommanded motor velocity as input. The microcontroller uses the velocitycontrol loop to compare the actual velocity of the motor to thecommanded velocity, and outputs a commanded pulse width modulation (PWM)command for the motor driver. At step 214, the commanded PWM value issupplied to the motor drive. At step 216, the motor drive changes theoutput current and moves the motor accordingly. At step 218, the motormoves, changing the position of the moveable arm.

FIGS. 13N-13Q illustrate tension control for a tether mechanism, inaccordance with exemplary embodiments. The tension control is used tokeep the tether under correct tension during takeoff, landing, andflight of the UAV.

FIG. 13N illustrates a high level flowchart for tension control for thetether mechanism, in accordance with an exemplary embodiment. Steps220-226 are performed on the microcontroller. At step 220, data andvalues from encoder(s) (e.g. motor encoder, spindle shaft encoder, etc.)are obtained. At step 222, necessary calculations are performed on theencoder values to determine a load on the torsion spring. At step 224, acontrol loop compares a position of a spindle shaft to a pulleyposition. At step 226, commands are transmitted to the motor to movesuch that a commanded position of the spindle compared to the pulleyposition is achieved, maintaining the desired load on the torsionspring.

FIG. 13O illustrates a differential encoder approach for tension controlfor the spooler, in accordance with exemplary embodiments. Steps 230-246are performed on the microcontroller. At step 230, an encoder value fora motor position is received. At step 232, an encoder value for aspindle shaft position is received. At step 234, a difference betweenthe position of the spindle shaft and the position of the motor iscalculated to determine the load on the torsion spring. At step 236, aposition control loop receives the calculated difference between thespindle shaft position and the motor position. The microcontroller usesthe position control loop to compare the actual position of the spindleshaft compared to the pulley position, and output a commanded velocityfor the motor. The commanded difference between the position of thespindle shaft and the motor is determined by the commanded tensionvalue. At step 238, a value from the motor encoder is received and anactual velocity of the motor in rad/s is determined. At step 240, afiltered value is passed to the velocity control loop. At step 242, thevelocity control loop receives the commanded motor velocity as input.The microcontroller uses the velocity control loop to compare the actualvelocity of the motor to the commanded velocity and output a signal fora driver for the motor. At step 244, the signal is supplied to the motordriver to move the motor to achieve the commanded position between thespindle shaft and the pulley. At step 246, the motor moves, changing aposition of the pulley compared to the spindle shaft

FIG. 13P illustrates a tension control feedback loop for the spooler, inaccordance with exemplary embodiments. Steps 250-266 are performed onthe microcontroller. At step 250, an encoder value is obtainedindicating an angle of the pulley to the spindle. At step 252, theencoder value is converted to radians and the angle value filtered. Atstep 254, the filtered angle value is transmitted to an angle controlloop. At step 256, the angle control loop receives the filtered anglevalue as input. The microcontroller uses the angle control loop tocompare an actual value of the angle to the commanded angle value, andoutputs a commanded velocity for the motor. The commanded angle value isdetermined by the commanded tension value. At step 258, a value from themotor encoder is obtained and an actual velocity of the motor in rad/sis determined. At step 260, the filtered value is transmitted to thevelocity control loop. At step 262, the velocity control loop receivesthe commanded motor velocity as input. The microcontroller uses thevelocity control loop to compare the actual velocity of the motor to thecommanded motor velocity, and outputs a signal for the motor driver. Atstep 264, the signal is supplied to the motor driver to move the motorto achieve the commanded angle between the spindle shaft and the pulley.At step 266, the motor moves, changing an angle of the pulley comparedto the spindle shaft.

FIG. 13Q illustrates a high voltage and low voltage board 600. In anexemplary embodiment, the board 600 converts 390 volts of direct current(VDC) from the power factor controller (PFC) and electromagneticinterference (EMI) board to 1070 VDC 48 VDC, 24 VDC, 5 VDC, and othervoltage rails that may be needed. The DC-DC topology chosen is linecommutated converter (LCC). This is a zero voltage switching (ZVS)resonant converter topology. The resonant converter topologies offermany benefits, particularly increased efficiency, which affects compactdesign, component size, heat generation etc.

FIGS. 13R-13U illustrate heat control mechanisms located within aportable housing for the tether system.

FIG. 13R illustrates a ducting layout 3600 for a tether deploymentsystem within a portable housing, according to an exemplary embodiment.The portable housing includes a thermally conductive plate 3602 (alsoknown as a cold plate), one or more air inlets 3603 from which toreceive air into the portable housing, and one or more air vents 3604from which to expel air from the plenum into the spool. A moveable arm3606 and a fan 3608 are mounted on a first side of the thermallyconductive plate 3602. In an example embodiment, a base controller ismounted on a second side of the thermally conductive plate 3602. Theplate 3602 acts as a heat sink.

In an exemplary embodiment, air flows from the fan 3608 and fan duct3609 into and across an air plenum 3610, directed by baffle walls tocover a maximum amount of surface of the plate 3602. The air exits theplenum 3610 though the one or more air vents 3604 (four rectangularholes), and into the spool plenum before traveling radially out, coolingthe tether.

FIG. 13S illustrates a bifurcated ducting layout 3700 for a spoolerwithin a portable housing, according to an exemplary embodiment. Thebifurcated ducting layout 3700 includes a fan 3708 and is configured todeliver a bifurcated air flow to provide forced convection within theportable housing. The portable housing includes one or more air inlets3703 from which to receive air into the portable housing and one or moreair vents 3704 (four rectangular holes) from which to expel air from theportable housing.

The air path from the duct is bifurcated into a first path and a secondpath. The first path travels radially out to the one or more air vents3704 into the spool plenum and exit radially from the spool, cooling thetether. The second path runs around the surface of the base plate andexits through a vent hole 3706. The advantage of this layout is that theairflow in the second path will not be impinged by the impedance of thetether when it is wrapped tightly on the spool. In one embodiment, aportion of the bifurcated air flow is directed to the base controlleraffixed to the second side of the thermally conductive plate. In someembodiments, the bifurcated ducting layout 3700 further includes atemperature sensor within the portable housing to monitor airtemperature, and a servo configured to control the bifurcated air flowby adjusting the relative portions of a first portion and a secondportion of the bifurcated air flow based on a monitored air temperature.

FIGS. 13T-13U illustrates a pressure relief ducting layout 3800 for atether deployment system within a portable housing, according to anexemplary embodiment. Similar to ducting shown in FIG. 13S, the coolingfluid (such as air) travels in series over a thermally conductive plate3802 into a spool plenum 3808 before entering one or more air vents 3704and traveling radially out through the spool 3806, cooling the tether.The spool plenum 3808 is located between the thermally conductive plate3802 and a cover plate 3804. In an event that the impedance of thetether wrapped tightly on the spool it too great and reduces the flowrate, the pressure will rise in the system. When this occurs, some airwill bleed off through a pressure relief valve 3802. This will result inadditional airflow in all parts of the ducting layout 3800. The pressurein the spool plenum 3808 is sufficient to result in adequate cooling ofthe tether.

In some embodiments, the ducting layout 3600, 3700, 3800 isservo-controlled, and includes an actuator that controls airflow todifferent areas of the spooler that need increased cooling. Inadditional embodiments, a humidity sensor is disposed within theportable housing and is communicatively coupled to a heat controlmechanism within the portable housing.

In some embodiments, the tether includes exterior ridges configured soas to provide additional openings for air flow when the tether is woundaround the tether retainer. The tether retainer is configured to acceptan additional element wound around the tether retainer in addition tothe tether so as to provide additional openings for air flow when thetether is wound around the tether retainer.

The system can be used, for example, to provide data used to avoid orprevent collisions between aircraft including airplanes, helicopters andUAVs operating within the airspace or to detect, track, classifypotential UAVs. The UAVs operating within the radar network can beprogrammed to adjust their positions or trajectories to avoid collisionswith other aircraft or objects such as buildings located within theiroperational airspace. Such a method 1400 is illustrated in FIG. 14A inwhich a radar assembly mounted on one or more UAVs is used to identifyand track objects. The UAVs can include high lumen LEDs forcommunication between network nodes. The LED emitters can be configuredto transmit controlled light patterns for low bandwidth datacommunication between UAVs. Thus, UAV nodes that are disconnected fromthe network, for example, can send real-time DTC data to and from othernetwork nodes.

The plurality of UAVs can be positioned in a specified stationarypattern or grid. The pattern can be any desired three dimensionalpattern such as where the UAVs are positioned equidistant from eachother in a plane at a specified altitude above the ground.Alternatively, one or more UAVs can be undergoing a specified movementrelative to each other, or the ground, or other airborne objects beingscanned by the radar system. The UAVs can also be positioned based onthe ground topography under the array of UAV radar nodes, or positionedrelative to structures such as buildings located underneath the array.The buildings can have a height that extends up to or above one or moreUAVs in the array. The UAVs can operate under independent control andcan change position within the radius defined by the maximum tetherlength from a fixed ground station. The tethered UAV can also belaunched from a moving vehicle as described in U.S. Pat. No. 9,290,269,the entire contents of which is incorporated herein by reference. Thisenables one or more UAVs as described herein to be moved to cover adifferent scanning region while remaining tethered.

A further preferred method of operating one or more UAVs involvesoperating one or more UAV radar nodes in autonomous mode, that is,without a tether. This can occur, for example, by detaching a tetherfrom a previously launched UAV or by launching a tetherless UAV toenable imaging and tracking of a moving object. A UAV launched toapproach or track another object such as an aircraft can employ a sensorthat receives reflected radar signals from an object and canautomatically move towards the object. The UAVs described herein can bemounted with acoustic or RF sensors that can identify the objects suchas other UAVs having known signature emissions. For example, a sensorthat can sense RF emissions in the range of 433 MHz to 6 GHz can be usedto identify other UAVs within a 1-2 km range.

The UAVs can employ different scanning methods based on their positionwithin the array. Each UAV can, for example, be instructed to scan agiven field of view by rotating in a full circular scanning pattern, orthrough a given angular range. A beamsteering circuit device can bemounted on the UAV that can be programmed to perform scanning of anumber of selectable scan areas or volumes at selectable resolution andsignal amplitude. This enables the use of one or more UAVs within thearray to focus on a particular region in which one or more objects arebeing actively tracked. Each UAV can use the flight control system torotate and/or translate the UAV in space to scan a particular field ofview, or use a gimbal mounted radar emitter to control beam direction,or can also use electronic scanning alone or in combination with one ormore of these scanning modes to control beam direction. An aerialvehicle including a mounted radar assembly 1420 and a camera 1422 can beconfigured on a gimbal along the central axis of the vehicle as shown inFIG. 14B.

A critical aspect for operation of a UAV launched radar assembly isrelative and absolute geographic location of the UAV. Unlike traditionalground based radar systems, where the position of each radar station isfixed, UAV based radar assemblies can alter position, including duringeach scan interval. This change in position can be continuous orperiodic for example. The global positioning system (GPS) coordinates ofthe UAV are frequently updated and transmitted with the acquired radardata so that system users can accurately identify the location andvelocity of identified objects at each scan interval. Thus, each UAV hasa GPS device mounted thereon to establish the UAVs position. Each UAVcan also have one or more motion sensors that can be used to provideestimated position data that is periodically updated if current GPScoordinates are not available. One or more onboard optical sensors orimaging devices can also be used to transmit data that can be used foridentifying UAV position. Additionally, other ground or UAV based radarassemblies can also determine a UAV's position when a GPS signal isbeing denied to the UAV either intentionally by malicious actors or forbenign reasons such as, but not limited to, geography, buildings andweather.

In one embodiment in which a GPS signal is denied to the UAV, forexample, such as may occur when the UAV is navigating indoors, amongtall buildings in a city environment, or when the UAV otherwise losesits ability to acquire a GPS signal, the GPS signal may be replaced bylocation data indicating the UAV's position that is based on radar. Forexample, in an embodiment, the location data may be provided by a basestation equipped with radar that is able to identify the UAV in itsradar field. The location of the UAV can be calculated by the controlstation based on the radar data in combination with the controlstation's knowledge of its own position. The calculated position basedon the radar may be communicated to the UAV for use in place of themissing GPS location data. In another embodiment, the base station maynot be equipped with its own radar but may be receiving radar data froma separate radar device that is able to track the UAV. The UAV'sposition may again be calculated using the radar data and the positionof the radar device and provided to the UAV for use in place of themissing GPS data.

It should be appreciated that other techniques may also be used tosubstitute radar-based location data for missing GPS data that do notrely on ground-based radar. For example, in one embodiment, the UAV maybe equipped with radar and may acquire other UAVs and/or the basestation with which it is in communication in its radar acquisitionfield. In such a case, the UAV may receive GPS or otherwise-derivedlocations from the other UAVs or the base station and use thatinformation in combination with the radar data to determine its ownposition. In another embodiment, the UAV may provide its radar data ofother objects with known locations to the base station which maycalculate the UAV's position and return the calculated position data tothe UAV. It will be appreciated that radar data acquired by the UAV ofother known positions can also be used by the UAV in combination withthe known position locations to provide substitute location data for theUAV when a GPS signal has been denied during UAV operation.

FIG. 14C depicts an exemplary embodiment with a UAV equipped with radarthat is communicatively coupled to other UAVs 1422 and 1424 that appearin its radar acquisition field. In the case of a GPS-denied situationaffecting UAV 1420 but not UAVs 1422 and 1424, UAVs 1422 and 1424 mayprovide their GPS location data to UAV 1420 which indicates theirrespective positions and UAV 1420 may cross-reference the provided GPSdata with radar data it has acquired that indicates the location of theother UAVs with respect to its current position in order to calculateits own location. The GPS data from UAVs 1422 and 1424 may be providedto UAV 1420 directly (e.g.: via wireless communication) or may betransmitted first to base stations (not shown) for UAVs 1422 and 1424and then forwarded to UAV 1420 via base station 1421 (e.g. over anoptical tether connecting base station 1421 and UAV 1420).

In one embodiment, the base station 1421 to which the UAV 1420 iscoupled may also provide location data to the UAV to use in place of thedenied GPS data. For example, base station 1421 may be located on and betransported by a vehicle 1462 and the vehicle 1462 may be equipped witha GPS device 1423. The GPS data from the GPS device 1423 that indicatesthe location of the vehicle 1462 may be provided to UAV 1420 over anoptical tether and be utilized by the UAV 1420 in determining itsposition. In another embodiment, the vehicle 1462 transporting the basestation 1421 may also be equipped with its own radar 1425 in additionto, or in place of, GPS device 1423. Radar 1425 may track UAV 1420 inits radar acquisition field and may supply the acquired data to UAV 1420over an optical tether (via base station 1421), wirelessly or in someother manner. It should be appreciated that in an alternateimplementation, radar 1425 may not be physically located on vehicle 1462but instead may be close enough in the vicinity to both track UAV 1420and communicate the radar data to the base station 1421 for forwardingto UAV 1420. In an alternate embodiment, radar 1425 may communicate theradar data indicating the position of UAV 1420 directly to the UAVwithout first transmitting the radar data to base station 1421.

FIG. 14D depicts an exemplary embodiment with UAV 1430 equipped withradar that is communicatively coupled to base station 1431. In the caseof a GPS-denied situation affecting UAV 1430, base station 1431 mayprovide its own location, derived via GPS or otherwise, to UAV 1430. UAV1430 may cross-reference the location data of base station 1431 withradar data it acquires indicating its position with respect to the basestation to calculate its own location. UAV 1430 may also utilizeadditional known information such as the current deployed length of atether connecting UAV 1430 to base station 1431 to determine itsposition.

In one embodiment, another UAV 1432, may be within a radar acquisitionfield of UAV 1430 and be coupled to base station 1433. UAV 1432 mayprovide its location, derived from its own GPS signal or otherwisedetermined, to its base station. Base station 1433 may be connected in awired or wireless manner to a network processor 1434 that is also incommunication with base station 1431. It should be appreciated thatnetwork processor 1434 may be integrated with a base station or may belocated in a separate computing device. Base station 1431 may receivethe location data indicating the position of UAV 1432 that was providedto base station 1433 from network processor 1434 and may communicatethat location data to UAV 1430 over an optical tether or in anothermanner. UAV 1430 may combine that location data with radar data it hasacquired that indicates the position of UAV 1432 to determine its ownposition.

In another embodiment, network processor may receive radar data from UAV1430 (via base station 1431) and GPS and/or radar data from UAV 1432(via base station 1433) and may perform calculations to determine thelocation of UAV 1430 using the received data. The calculated positionmay be forwarded to UAV 1430 via base station 1431 to be used by UAV1430 for navigation and/or data acquisition purposes.

In one embodiment, UAV 1430 and UAV 1432 may both be tracking aerialobject 1435 via onboard radar or other sensors such as acoustictransducers or imaging devices that can be used to identify and trackmoving objects. For example, aerial object 1435 may be a plane,helicopter, balloon, missile or other airborne object being jointlytracked by UAV 1430 and UAV 1432. UAV 1432 may communicate its radardata regarding aerial object 1435 to UAV 1430 via base station 1433,network processor 1434 and base station 1431. UAV 1430 may combine theradar data received from UAV 1432, with its own acquired radar datarelating to aerial object 1435 and other determined location data forUAV 1432 (e.g. a radar determined location or GPS provided location fromUAV 1432) to determine its own position. In an alternate embodiment, UAV1432 may transmit its acquired radar data relating to aerial object 1435and/or its GPS data directly to UAV 1430 rather than transmitting theinformation via base station 1433, network processor 1434 and basestation 1431. In one embodiment, UAV 1430 and UAV 1432 may provide radardata from tracking aerial object 1435 to network processor 1434 in orderfor network processor to calculate a current position of UAV 1430.

FIG. 14E depicts a UAV 1440 that is coupled to base station 1441. Basestation 1441 is in communication with network processor 1444 and radardevice 1445. Similarly, UAV 1442 is coupled to base station 1443. Basestation 1443 is also in communication with network processor 1444 andradar device 1445. UAV 1442 may provide its own GPS derived location tonetwork processor. Radar device 1445 is able to acquire UAV 1440 and UAV1442 in its radar acquisition field and may provide radar data tonetwork processor 1444. Radar device 1445 may also provide its ownlocation, derived via GPS or otherwise, to network processor 1444 tocross-reference with the radar data (and optionally GPS data obtainedfrom UAV 1442) to calculate a position for UAV 1440 which may bereturned to UAV 1440 for navigational and/or data acquisition purposes.

It will be appreciated that the above-examples of calculating asubstitute location for a UAV when the UAV loses a GPS signal areillustrative rather than exhaustive and that other approaches are alsopossible within the scope of the current invention. For example variousforms of radar, lidar and other sensing technologies may be used withoutdeparting from the scope of the present invention.

In one embodiment, when a GPS signal is denied to the UAV the UAV maydetermine its altitude, location and/or orientation with the assistanceof one or more IR LED emitter arrays or solid state laser arrays(hereafter “emitter arrays”) provided in one or more small ground-basedmodules. In an embodiment, the modules may be circular in shape and 3-5inches in diameter. FIG. 14F depicts an exemplary emitter array 1450 inan embodiment. An optical sensor deployed on the UAV may detect thesignal projected from the emitter array(s) and determine the altitude,orientation and/or location of the UAV based on detected signal strengthfrom a single or multiple emitter arrays and/or by triangulating signalsreceived from multiple emitter arrays. In one embodiment, a signalemitted from the emitter arrays may be detected by the UAV at least at adistance of 150-200 meters.

The one or more emitter arrays may be deployed in a number of differentlocations. For example, in one embodiment, depicted in FIG. 14G, one ormore emitter arrays 1471, 1472 and 1473 may be integrated into a mobilelanding platform 1468 that is coupled to a housing 1463 that encompassesa base station 1464 and spooler 1466 connected to UAV 1460. The housing1463 is supported (and transported) by a vehicle 1462. In someembodiments, the spooler 1466 may be a passive spooler or a spoolercontrolling tension on the optical tether via a torsion spring. FIG.1411 depicts a top view of the mobile landing platform 1468 withintegrated emitter arrays 1471, 1472 and 1473 and vehicle 1462. Anoptical sensor on UAV 1460 may utilize the signals propagated by emitterarrays 1471, 1472 and 1473 to determine its position, orientation and/orto land on the mobile landing platform. For example, in an applicationwhere a UAV must follow a moving vehicle, boat, or towed landingplatform, the signals from the emitter arrays in the mobile landingplatform will allow for precision takeoff/landing using a local X-Yposition reference frame and altitude/orientation computation.

The one or more emitter arrays may also be deployed in a number ofalternative locations instead of being integrated into a mobile landingplatform. In one embodiment, an emitter array is attached to a spoolerproviding the optical tether to the UAV 1460. In another embodiment, alanding zone may be surrounded by multiple emitter arrays. Alternativelymultiple ground-based emitter arrays may be deployed but not mark alanding zone. In one embodiment, a vehicle transporting a base stationand spooler may also be equipped with one or more emitter arrays.Similarly, a stationary base station may also include one or moreemitter arrays. It should be appreciated that the above examples ofemitter array locations are for illustration and other emitter arraylocations are also within the scope of the present invention.

The optical sensor onboard the UAV may be coupled to a dedicatedprocessor for processing image data. For example, in one non-limitingexample, the optical sensor may be a CMUcam5 Pixy™. The optical sensormay use a standard 5MP imager, decimated down to a 300×200 image sizeand standard small M12 lenses with 2 additional filters between the lensand sensor chip. One filter may be a 950 nm+/−5 nm IR narrow bandpassfilter, while the other filter may be a wide pass filter only used forfrequencies above 800 nm. The lens may be slightly defocused to allow agreater diameter defocused “blob” to be imaged, e.g. when detected atlong distances, even a 100 mm emitter array can appear as a pointsource. Defocusing is needed if the optical sensor requires a contiguous2×6 pixel area to be detected. It should be appreciated however thatother readout methods can be employed, as well as linear X-Y PSD sensingdiodes in lieu of a CCD/CMOS imager array.

In one embodiment, the optical sensor samples and decimates at 50 hz andan embedded ST processor reads this result into RANI for analysis. At200 imager rows, this is 100 microsecond per row readout. Therefore, inone embodiment, the emitters in the emitter array may be configured toflash at 100 microsecond, or 10 khz. The clocks at the emitters andoptical sensor drift and are not exact phase or frequency aligned whichcauses a low frequency aliasing or beat frequency to occur in the imageframe. To counteract this occurrence, the frequency may be ditheredevery frame, or every 20 ms, to remove long term frame to framealiasing. The system is very intolerant of specific dithering, and canbe randomized.

The UAV may use the data acquired via the optical sensor to track itsposition, height and/or orientation in place of the missing/denied GPSdata. Altitude can be roughly estimated by the received pixel “blob”intensity since the “blob” gets smaller and less intense with distance.This distance measurement range is 10-100× that achievable with SONARtechniques, for example. Even at distances where the baseline emitterarrays cannot be resolved to compute a distance, each emitter array canbe alternately “strobed” at below 50 hz, so that an exact sub-pixel“blob” centroid can be computed. This results in 1030× improvement inresolution capabilities. Since the optical sensor is programmed to see asmall (<5%) intensity change between successive frames on the same“blob”, modulating the LED emitters to meet this criteria results inzero false positives. Thus, sunlight, and reflections from water/movingautos, snow, etc. have limited effect.

The UAV may be provided with one or more optical sensors in one or moreconfigurations. For example, in one embodiment, the UAV may be deployedwith a single gimbaled optical sensor with a 12 mm focal length lensthat reduces baseline requirements to about 1 meter. With the gimbaled12 mm focal length lens, ground coverage at 125 m is 11.1 deg×7.6 degand 30 m×17 m. With a shorter gimbaled optical sensor with a 2.8 mmfocal length lens ground field coverage of 71 deg×47 deg and 181 m×100 mat 125 meters is provided. Alternatively, the UAV may be deployed with 2optical sensors (which weigh less than 1 gimbaled optical sensor) withdiffering focal lengths to cover both low and high altitude with similarabsolute position error. In an embodiment the emitter array providesgreater than 40 W of optical power. Additional optics may be used over awide angle LED to collimate a beam resulting in an increase in opticalflux.

In addition to enabling a UAV to determine its location, orientationand/or altitude, the emitter array is also able to act as an opticaltelemetry emergency system for RF communications loss thereby providingan additional way to communicate with the UAV from the ground. Whilejamming usually takes out all RF communications, including WIFI, ISMfrequencies and navigation frequencies, optical modulation can betransmitted at a 10 kHz rate in the event emergency instructions areneeded to reach the vehicle.

The exact configuration and deployment of the light emitter arrays mayvary depending upon the UAV's flight mode. For example, a wide beamarray (with no reflectors) may be used for gusty or on the movelandings. A main high power beam may be used for high altitude operationusing collimated reflectors. Less optical power may be used at a lowaltitude such as when the UAV is landing. During gusty conditions,pitch/yaw extremes can cause jitter with narrow (10 degree) optics andso divergence is increased to +/−20 degrees. In an embodiment, opticalpower from the emitter arrays can be programmed by a user depending onflight modes, conditions and the performance required. For example, theemitter array may accept RS232 commands and data streams from acontroller and may allow a 20:1 change in output power on each of 3individually addressable LED channels. In one embodiment, the emitterarrays are communicatively coupled with the OCU (e.g., OCU 50 in FIG. 1)which may provide a user interface to adjust the emitter array settings.Since LED's can be easily damaged by overcurrenting, a circuit may beprovided to limit the safe LED current. The LED's can be safelyoverpowered when in low duty cycle operation (up to 5× the optical powerover DC conditions). Heat may be removed by a low thermal resistancealuminum or copper core PCB which is fan cooled. LED power andtemperature as well as error/warning messages may be passed to thecontroller from the emitter array.

In an embodiment, the LED power may be modulated to requirements of theunsynchronized emitter arrays and the receiving optical sensorcapabilities. In an exemplary emitter array, a “HI” signal with aprogrammable fixed period may be used to drive a Mosfet ON and causecurrent to flow. The longer the ON time, the higher the emitted powerfrom the array and longer the range of the emitted signal. The low time(when the HI signal is not being provided) is modulated. All 3 channelscan be active simultaneously since all start HI at the same time. Thisapproach maximizes the total optical power over wide and narrow beams.Individual arrays/elements can be strobed. The optical sensor can trackseveral simultaneous objects as long as there is modulation present.Thus two or more ground beacons separated at a given baseline allow fortriangulation of height, and/or vehicle orientation. It will beappreciated that the above-examples of IR LED or solid state laseremitter arrays are illustrative rather than exhaustive and that otherapproaches are also possible within the scope of the current invention.

A power management system on board each UAV can be used to allocatepower most efficiently to the systems being utilized at any given time.One or more onboard processors can be used to monitor and allocatepower. If additional power is needed, for example, the system allocatespower to enable use of the radar system to track a particular target andalso operate other on board sensors, such as a CCD, CMOS or infraredimaging device to generate images of one or more detected objects withinthe scan area. Thus, an onboard power management processor can beprogrammed to employ a software module that is configured to instruct apower management controller to allocate power based on a prioritizedranking of tasks to be performed. A more power consuming radar scanningprotocol, for example, can cause the controller to limit power to otherUAV operations without impacting flight control. The system user can bealerted to circumstances in which power thresholds are exceeded andnecessitate power limiting operations. Under certain circumstances, thetethered system can be flown in autonomous mode, for example. In thesecircumstances, power utilization and control will operate based ondifferent criteria than in powered tether mode. In other circumstances,when operating based on power supplied by the tether, the system can beconfigured to also utilize onboard battery power that is available tosupplement the tethered power level.

The system can also include systems and methods for data fusion of datagenerated by one or more of the UAVs in the array. In a preferredembodiment, radar generated data such as velocity data associated withan object being detected and/or tracked by a first UAV mounted radarassembly can be processed with radar generated data including velocitydata associated with the same detected object by a second UAV mountedradar assembly. Due to the speed, trajectory, elevation and distance ofa detectable object from each element in the UAV radar array, each unitin the array can generate a different velocity value for the object ateach point in time. It is desirable to generate more accurate velocityand position information regarding the detected object by altering thescan parameters of one or more of the UAV radar assemblies in subsequentscan intervals. It can be desirable for example, to select a subset ofthe available UAV radar units to which have its scan parameters revisedin subsequent scan intervals to select a given object for tracking.

A critical aspect for operation of a UAV launched radar assembly isrelative and absolute geographic location of the UAV. Unlike traditionalground based radar systems, where the position of each radar station isfixed, UAV based radar assemblies can alter position, including duringeach scan interval. This change in position can be continuous orperiodic for example. The global positioning system (GPS) coordinates ofthe UAV are frequently updated and transmitted with the acquired radardata so that system users can accurately identify the location andvelocity of identified objects at each scan interval. Thus, each UAV hasa GPS device mounted thereon to establish the UAVs position. Each UAVcan also have one or more motion sensors that can be used to provideestimated position data that is periodically updated if current GPScoordinates are not available. One or more onboard cameras or imagingdevices can also be used to transmit region that can be used foridentifying UAV position. Additionally, other ground or UAV based radarassemblies can also determine a UA s position.

Further embodiments can be used to enable use of additional UAVs thatare not radar equipped to be launched or instructed to move to aposition in closer proximity to an object identified by the radarnetwork to track the object or obtain images of the object, such as aUAV, that is crossing the scanned airspace.

Radar assemblies that can be used to a single radar node or multimodeUAV system are available from Echodyne, Inc. Such devices and methodsare described in U.S. Pat. No. 9,268,016, the entire contents of whichis incorporated herein by reference. The radar panels can be flat orshaped to provide control over steering a high gain beam. The emitterpanel comprises a two or three dimensional array of elements that areswitched or on off in a controlled pattern. The emitter array cancomprise a printed circuit board emitting in a range of 5 GHz to 33 GHz,for example.

The UAV radar network can utilize multipath reflections from buildings,for example, to scan spaces between buildings that extend beyond adirect line of sight (LOS) detection path. Thus, non-LOS methods can beemployed to detect objects. A classification protocol can be employed inwhich one or more attributes of a detected object is used tocharacterize and/or identify a detected object within a networked UAVsensor system field of view. Objects within the field of view of a UAVnode that are known can include a reflector device that reflects the UAVnode radar signal. This operates to simplify classification of knownobjects, such as other UAVs within the network. Pattern recognitionalgorithms can be used to assist in the classification process.

FIG. 141 illustrates a ground station 702 reeling in an UAV 704 with adeployed parachute 706. The ground station 702 pulls the UAV 704 intothe ground station 702 while the UAV 704 is descending after a parachuteor motor out descent.

During a system flight there may be a time when the parachute 706 may bedeployed, or the UAV 704 will experience a motor out event. In thissituation, the UAV 704 is in a parachute or motor out descent. Theground station 702 then begins reeling in filament 708 and pulling theUAV 704 mass toward a filament intake of the ground station 702 whilethe UAV 704 descends. This controls a location where the UAV 704 touchesdown, mitigating risks of the uncontrolled descent.

FIG. 14J illustrates a pivoting tether hoop 800 attached to an UAV, inaccordance with an exemplary embodiment. The hoop 800 is configured toswing on one axis and includes a movable attachment for the tether. Insome embodiments, the hoop 800 has straight arms; in other embodiments,the arm may be curved. In an exemplary embodiment, the angle of thetether to the center of gravity is between 25-30 degrees. The tethervector preferably intersects the center of gravity of the UAV andpayload. This ensures that the tether does not apply a moment to theUAV. Because the center of gravity is above the payload plate(approximately in the battery area), the tether vectors are as close aspossible. The hoop 800 is designed to have the tether vectors intersectat the highest possible point given the chosen pivoting hardware (i.e.,ball joints, McMaster 59935K13, etc.).

FIGS. 14K-14M illustrate attachments for connecting a pivoting tetherhoop 800 to an UAV. FIG. 14K illustrates an attachment 902 forconnecting a pivoting tether hoop 800 to a plate 903 on an UAV using arod end ball joint 904. The rod end ball joint enables a 180 degreeswivel. FIG. 14L illustrates an alternative view of the attachment 902for connecting a pivoting tether hoop 800 to a plate 903 on an UAV usinga rod end ball joint 904. FIG. 14M illustrates an attachment 906 forconnecting a pivoting tether hoop 800 to a plate 903 on an UAV using aUniversal joint 908. The Universal joint 908 axes are inclined to eachother, and are used to enable rotary motion in the pivoting tether hoop800.

FIG. 14N illustrates an Integrated Delivery Function (IDF) system 1000,according to an exemplary embodiment. The IDF system 1000 includes aportable spooler and base station 1001, as described herein. The station1001 is a weather-proof, self-contained housing that includes a basestation 1002, a spooler 1003, and a power source 1004. The station 1001further integrates base station electronics within the housing. Thestation 1001 provides control and spooling of the filament, as well ashouses the power and communication to an UAV 1007.

In some embodiments, as illustrated in FIG. 14N, the station 1001further includes an internal landing platform 1006 and the UAV 1007. TheUAV 1007 includes an onboard computer and a tether connected to the basestation 1002 that provides data communication and/or power to the UAV1007. A tether mechanism includes a tether controller that deploys thetether during flight of the UAV 1007. The base station 1002 includes abase controller having at least one processor.

The landing platform 1006 includes an opening 1005 (also known as atether guide 1005) in a center of the landing platform 1006. The landingplatform 1006 (as shown in FIG. 12) is used for the take-off and/orlanding of an UAV 1007. A tether runs from the spooler 1003 through apulley if needed and through the tether guide 1005 in the center of thelanding platform 1006 to connect to the UAV 1007. The tether guide 1005is mounted on a vertically moveable mechanism, which moves within thelanding platform, 1006. In FIG. 9, the tether guide is shown mounted tothe platform 1006 on a linear rail system. In FIG. 12, the tether guideis shown as a large disk with a hole in it mounted on a linkage system,1308. The landing platform lift mechanism is separate from the tetherguide lift mechanism 1010.

The landing platform 1006 is lifted by a power mechanism in order tobring the UAV, 1007, above the height of the container, 1001, or otherobstructions, to provide clearance for a safe take-off or landing. Thetether guide, 1005, has the purpose of controlling the precise positionof the UAV as it makes contact with the landing platform and to preventlateral movement as the UAV takes off. Because the point where the UAVcontacts the landing platform may be above the tether attachment point,it may be advantageous to have the tether guide move vertically withrelation to the platform. This movement may be by spring force or acontrolled power actuator. In some embodiments, the IDF system 1000system includes a retractable roll top cover 1009 for covering theinternal compartment of the station 1001. In an exemplary embodiment,the landing platform 1006 includes an actuator 1010 (also known as alifting mechanism) that is spring loaded and extends upward via poweredmotor. In alternative embodiments, spring pressure is employed.

Before deployment, the UAV 1007 is located on the landing platform 1006and fully contained inside the station 1001 (a stowed position). The UAV107 held in place by a taught tether connected to the UAV 1007 throughthe tether guide 1005. As the UAV 1007 is being prepared for deployment,the landing platform, 1006 and the tether guide, 1005, are raisedtogether to the launch/land position. In an exemplary embodiment, apower actuator will raise the platform, 1006 and guide, 1005 to thelaunch/land position. In an alternate embodiment, the platform couldhave a spring to raise it and it may be held in a lower position by thetether tension or the weight of the UAV. The lifting motion could beprovided by the UAV propellers or from a reduction in the tether tensionfrom the spooler. During a take-off, the UAV 1007 lifts off of thelanding platform 1006 but the tether guide 1005 maintains contact withthe UAV, preventing it from any lateral excursion. The Tether guidecontinues to extend until the lowest portion of the UAV is clear of thelanding platform 1006.

During landing, the UAV 1007 is drawn in towards the central axis of thelanding platform 1006 by the tension of the retracting tether via thetether guide 1005. Once the UAV 1008 is in contact with the guide, apower actuator or the weight of the UAV 1007 and/or the tension in thetether causes the guide to retract with the UAV 1008 until contact withthe landing platform is achieved. Once the UAV 1007 lands on the landingplatform 1006, the landing platform 1006 and UAV 1007 are retracted intothe station 1001. The tether guide 1005 maintains ideal alignmentbetween the UAV 1007 and the center of the landing platform 1006.

In some embodiments, the IDF system 1000 is integrated into a fixed,transportable, or moving mode of deployment, including but not limitedto towed trailers, ground vehicles of all types, and maritime vessels,as well as single-point semi-permanent emplacements. This enables theIDF system 1000 to be transported safely and under protection from theelements, and for the UAV 1007 to take off and land safely andautonomously from/at a precise point. In addition, the IDF system 1000is also designed for air vehicle deployment while a ground vehicle, amaritime vehicle or watercraft is static and/or in motion, and tomaintain optimal tether dynamics while both air vehicle and carriervehicle are moving together in tandem. This enables the air vehicle tolaunch and/or land from the moving landing platform 1006 or flight whilethe carrier vehicle is moving. The thinness and lightness of the tethercauses the tether to be less susceptible to wind distortion.

In an exemplary embodiment, the tether and base controller areconfigured to deliver approximately 1000 volts to the air vehicle. Inanother embodiment, the tether and base controller are configured todeliver more than 1000 volts to the UAV. One or more high voltagetransformers are connected to the portable housing to isolate anelectrical charge.

FIG. 140 illustrates a side view of the IDF system 1000 shown in FIG.14N. FIG. 14P illustrates an angled view of the IDF system 1000 shown inFIG. 14N.

It should be noted that the locations of the components in the portablespooler and base station 1001, including the spooler 1003, the powersource 1004, and the base station 1002, are for illustrative purposesonly and may be located in different locations and in differentconfigurations.

FIG. 14Q illustrates the internal landing platform 1006 of the IDFsystem 1000, according to an exemplary embodiment. The lifting platformincludes an outer ring 3302, an inner ring 3304, and a tether guide3306. In an exemplary embodiment, the outer ring 3302 of the liftingplatform 1006 is actuated by a motor. In other embodiments, the outerring 3302 may be actuated by hydraulics or pneumatics or other means.The inner ring 3304 moves independent to the outer ring 3302 either byits own actuator or by a spring mounted in a way to push the outer ring3302 upwards. The inner ring 3304 with the tether guide extends furtherto be above the height of the outer ring 3302.

FIG. 14R illustrates a mobile delivery system 100 for an unmanned aerialvehicle (UAV) 102. The mobile delivery system 100 includes the IDFsystem 1000, described above. In the illustrated embodiment, the IDFsystem 1000 is mounted on a vehicle 104. In one embodiment, the IDFsystem 1000 is disposed in a recessed compartment on the vehicle 1104that includes a retractable top surface over the recessed compartment.

To enable rapid deployment of airborne payloads (sensors, cameras,communications repeaters, or other gear), there is a need for a tetheredor non-tethered UAV 1007 that can be transported safely and underprotection from the elements, and that can take off and land safely andautonomously from/at a precise point. This capability is typically usedwith fixed, transportable, or moving modes of deployment, including butnot limited to towed trailers, ground vehicles of all types, andmaritime vessels, as well as single-point semi-permanent emplacements.

In some embodiments, the mobile delivery system 100 uses a static andground system. The static and ground system includes a grounding wire106 attached to stakes 108. The base station for the UAV 102 include oneor more grounding lugs 110 connected to an end of the grounding wire 106and configured to dissipate excess electrical charge. The tethermechanism is grounded via a cable going from the base station to thetether mechanism. In some embodiments, the housing for the tethermechanism includes conductive feet.

In an exemplary embodiment, the stakes 108 form a ring around thevehicle 1104 and/or UAV 102. The mobile delivery system 100 is designedprimarily for use with systems requiring high mobility. The stakes 108are easily emplaced and removed, offering a reasonable option insituations where driving/retracting conventional ground rods would bedifficult and/or too time consuming. In an exemplary embodiment, thestakes 108 have a combined stake surface area approximately 50% greaterthan a standard 8-foot ground rod. Hence, the mobile delivery system 100provides a path to the ground with significantly lower resistance.Resistance is further reduced through additional contact area providedby the wire 110 routed between the multiple stakes 108, as shown in FIG.13. In one embodiment, the grounding wire 106 is 3/16 galvanized steelcable. The mobile delivery system 100 includes four 2′ stakes 108 (orelectrodes), each located 5 feet apart, for a total length of 20′ of3/16 galvanized steel cable. The mobile delivery system 100 is asecondary measure when using a generator. The generator's frame isconsidered a ground, however, using the supplemental stakes 108 improvethe ground conditions for static dissipation.

FIG. 14S-14T illustrates views of a brush box 4600 that includes brushes4602, according to an exemplary embodiment. The brush box 4600 is acompartment on an intake of a spooler designed to slow the tether in theevent that it is feeding in from above at a rate higher than the spoolmechanism can take up. The brush box 4600 further removes dust andstatic electricity. The brushes 4602 are conductive and sitting in aplastic (non-conductive) box 4604; thus, a bare wire 4606 is anchored ata top of the brush box 4600 and runs through the bristles and isgrounded by a mounting screw at a bottom of the brush box 4600.

FIGS. 15A-15F depict an exemplary PARC system. Illustrated in FIG. 15Ais an exemplary system for operating a tethered aerial vehicle using anoperating control unit (OCU) 1502, a control or base station system 1505that can have three primary components including a networkedcommunication module 1504 that transmits and receives communicationsignals, a high voltage transmitter 1506 that delivers high voltageelectrical power to a tether that is dispensed and retrieved with atether dispensing unit 1518 such as a spool assembly 1520 that isoperated by spooler control system 1522. The spooler controller 1522receives power from the third base station component, a base stationpower source 1508. A modem 1510 is used to format electrical signals fortransmission to the aerial vehicle 1512 with the tether. A filter 1515can be used to prevent the transmission or reception of signals outsideof operational constraints. The aerial vehicle can carry a payload 1514such as a camera or other type of sensor or electrical or optoelectronicdevices, or combinations thereof. More detailed illustrations of thebase station 1505 are shown in FIGS. 15B and 15C. The station 1505 canhave a control panel 1520 that the user can use to operate and monitorthe system, Optical 1522 wireless, and wired 1524 links can be usedinterface with the control station. The internal elements include aprocessor 1526 linked to single board computer 1530 that controlsEthernet switch 1532. Converter 1534 delivers power to the high voltageboard 1528. The signal delivered to the filament 1538 is managed bycontroller 1536 which can include a Xilinx FPGA (Kintex 7 Base) or otherintegrated circuit design configured to precisely control the highvoltage power delivered to the aerial vehicle with the filament 1538.The FPGA can be viewed as a block that converts Ethernet network trafficto a communication protocol and bus that can be transmitted over atwisted pair interface.

An embodiment of a tether dispensing unit 1518 is illustrated in FIG.15D. This system includes microcontroller 1540 that operates the motors,steppers and additional control elements. The system rotates a spool1548 in this embodiment with a motor assembly 1546. The encoder 1550reports the amount of the filament dispensed with counter 1552. Thespool shown in FIG. 15E can employ slip ring 1560 to control placementof the filament onto the spool. The dancer encoder 1544 can be used tosense the tension in the dispensed tether. This tension sensor isoperative to precisely regulate the amount of slack in the tether duringflight. The location of the spooler can be determined with GPS sensor1562, for example, which enables the processor to approximate therelative distance between the aerial vehicle (which sends updatedgeographic position data back through the tether or by wireless link)and the tether management system.

Illustrated in FIG. 15F is a control system 1575 for the aerial vehicle.The tether is used to deliver high voltage DC power to the vehiclecontrol system and also provide AC communications to and from thevehicle. The tether is linked to a triplexer circuit 1576 which routesthe high voltage DC signal to the DCDC converter 1577 which regulatespower to the payload 1578, the parachute deployment circuit 1579, thesystem processor 1580, the inertial measurement unit (IMU) 1582, themotor control circuit 1583, and SBS circuit 1584 that providesgeographic location data on the position of the vehicle at periodicintervals. The vehicle location circuit 1584 delivers GPS (GNSS) datafrom a GPS receiver and pressure sensor data indicative of the altitudeof the vehicle. The triplexer circuit 1576 also delivers communicationsignals from the control station to the vehicle to control operation ofthe vehicle and the payload. The triplexer also routes data from thevehicle to the control station including sensor data, payload data andtelemetry from the aerial vehicle to the control station. The processor1580 includes a memory for storing instructions to control flightoperations of the aerial vehicle. A battery 1585 provides power to thesystem during start-up and during flight when power from the tether isdisconnected. The system power switch 1586 actuates PDR circuit 1587that regulates power from the battery until the high voltage signal fromthe tether takes over.

In some embodiments, vehicle power management systems can be employed tocontrol flight operated sensing and communication features of the aerialvehicle. These features are preferably used in tethered UAV, that alsocan operate with one or more batteries. In one embodiment, an unmannedaerial vehicle draws power from either ground sources (via tether), fromon-board batteries, or from both, as required by operator command or byautonomous control. This ability allows, among other features, aground-powered aerial vehicle to have a power source for safe,controlled landings upon interruption of ground power. Embodiments mayhave one or more of the following power management features in which aswitching circuit is used to improve power distribution.

The unmanned aerial vehicle may use power mediating strategies. Theunmanned aerial vehicle may use a back-up battery to power the vehiclein the event of DC power loss, for safe landing. The unmanned aerialvehicle may use back-up battery power to initiate the start-up sequenceprior to vehicle launch, in advance of power flow from a ground source.The unmanned aerial vehicle may use a ground-based power source tosupply the vehicle, its payload(s) and associated electronics while inflight, without drawing upon battery resources. The unmanned aerialvehicle may use a ground-based power source to recharge the aerialvehicle's battery during flight, enabling that on-board source to beready against need. The unmanned aerial vehicle may use battery power tosupplement ground-based power, in the event of increased temporary powerdemand, as commanded by human initiation or autonomous flight control.In some examples, the load demand of the unmanned aerial vehicle mayreduce the voltage on DC/DC, causing the battery to automaticallyconnect in parallel (with the filament acting as a balancing resistor).

Need may arise in which it becomes desirable for an aerial vehicle touse more than one power source during operation, or to switch from onepower source to another. For example, a tether may be compromisedleading to an interruption of ground power, and the vehicle may need todraw upon battery power to enable a controlled, safe descent andlanding. In some examples, power interruption is unplanned. For example,a fuel powered generator may run out of fuel causing an unplanned powerinterruption, the generator may fail, a line connecting the generator toa base station may be compromised, the base station may fail, a filamentline may fail, connectors between the filament and the base station, orthe filament and the UAS, or those between the cable connecting the basestation and spooler may become loose or disconnect entirely, or thecable between the base station and spooler may fail or be compromised.

In some examples, power interruption is planned. For example, thegenerator may be deliberately powered down to allow for safe refueling,power may be interrupted for debugging purposes, power may beinterrupted for battery performance verification, or an operator maypress the system emergency switch (E-Stop) if he or she senses threats,including someone unauthorized inside the operational safety perimeter,someone (or something) at risk of contacting the filament, inclementweather, etc.

Aerial vehicles may require additional power capacity to meet surgerequirements resulting from manual, pilot-issued or autonomouslytriggered flight commands. For example, an aerial vehicle may need toaccomplish a steep climb requiring power beyond that supplied by itsground power source. To meet this surge demand it may need to augmentground power with additional stored power from its on-board batteryreserves.

Aerial vehicles may require ground-based power to replenish batterieswhile in flight, using a recharger drawing upon ground power to rechargethe batteries, while simultaneously using that ground-based power forlocomotion, maintaining altitude, communications, sensor/payloadoperations, or vehicle command and control. The ability to constantlyrefresh the battery and maintain its charge allows the battery to be ofsmaller size/weight/capacity than would be a non-replenished battery,and still fulfill its primary mission of providing emergency or surgepower.

Therefore, there is need for a small-footprint mechanism capable of useon an aerial vehicle, which can intelligently handle intermediatevehicle power needs, drawing upon multiple sources and routing powerfrom those sources, as required by manual pilot or autonomous control.Designing such a small-footprint mechanism required identification andqualification of circuits capable of high power switching (a fewkilowatts), minimal heat generation (losses), minimal weight, minimalsize, fast switching (under lOus), and non-interrupting switching.

Embodiments may relate to the use of power mediating strategies on anunmanned aerial vehicle that employs two power sources, that enables useof one or both sources as needed, and allows switching between thosesources as needed. Embodiments may allow an unmanned aerial vehicle touse a back-up battery to power itself in the event of the loss of itsmain power source (in one case, DC power provided via tether), for safelanding. In turn, this allows safe, controlled and powered landing incase of an emergency, including but not limited to tether breakage, orfailure of the ground source.

Embodiments may allow a tethered vehicle to start-up from battery powerprior to recognition of power from a ground source. Embodiments mayallow supplementation of ground power with power from the battery, tomeet surge power demand (for example, if rapid climb is requested byhuman-initiated or autonomous operations). Embodiments may allowcontinuous recharging of the aerial vehicle's battery in flight, drawingupon power from the ground source, so that battery capacity is alwaysready and available when needed. In one embodiment, ground-based powermay be limited based on average power and/or effect on the tether. Forexample, ground based power may be limited to avoid overloading thetether.

In one embodiment, the aerial vehicle body assembly 301 may house systemelectronics including on-board circuitry such as power conversioncircuitry, vehicle control circuitry, and sensor circuitry in anenvironmentally sealed enclosure. The system electronics may performpower mediating operations.

FIG. 15G is an illustration of a control and/or communications systemschip 2000 for the spooler and base station 1001. The control and/orcommunications systems chip 2000 can be a single chip solution forHD-PLC applications. The KL5BPLC200WMP integrated circuit is an HD-PLCLSI designed to connect a wide range of network devices in a flexiblemanner using existing electrical wiring. Its capabilities includetransmission of high-definition video and other broadband content.HD-PLC refers to a high definition power line communication system. Inan exemplary embodiment, the chip 2000 is a KL5BPLC200WMP single chipIEEE 1901 HD-PLC Powerline Communications (PLC) IC by MegaChips in SanJose, Calif. The chip provides a small form factor, high performance,low power, robust communications, superb noise immunity, and highquality of service (QoS) over both AC and DC power lines. Other chipoptions include Broadcom BroadR-Reach transceiver that is compliant withthe IEEE 802 and related standards. In one embodiment, both the basestation 1001 and the UAV includes a control and/or communicationssystems chip 2000 to provide the same or similar processingcapabilities. The control and/or communications systems chip 2000includes the following components.

A general purpose IO 2010 is linked to a UART serial interface to the onboard processor 2012, and an on chip timer peripheral 2014 with a bus.An on-chip direct memory access controller 2016 that manages the methodthat allows an input/output (I/O) device to send or receive datadirectly to or from the main memory, bypassing the CPU to speed upmemory operations. An on-chip peripheral 2018 is used to combine severalsources of interrupt onto one or more CPU lines, while allowing prioritylevels to be assigned to its interrupt outputs.

An on-chip RISC microprocessor 2020 can be used for primary processoroperations. In an exemplary embodiment, the microprocessor 2020 is anARM946E-S™, which is a synthesizable processor combining an ARM9E-S™processor core with a configurable memory system. It is a member of theARM9E™ family of high-performance, 32-bit system-on-chip processorsolutions. A PLC physical layer interface 2022. The PHY connects thelink layer device (MAC 2002) to the physical medium Analog Front End(AFE) 2024 which is in the path to the copper and optionally opticalfiber cable in the tether. An analog front end chip 2024 is highlyintegrated and enables a system in which no other analog front-end ICfor PLC is necessary. Power line communication medium access control2002 provides flow control and multiplexing for the transmission medium.

The chip 2000 includes a complete implementation of IEEE 1901 and HD-PLCMAC/PHY and a fully integrated Analog Front End (AFE) with highprecision A/D, D/A data converters and programmable gain amplifiers(PGA). The chip further provides low power consumption under fulloperation, and also includes a power save mode. The Power SpectralDensity (PSD) is fully programmable to enable the chip to comply withregional requirements.

The chip 2000 includes a PLC media access control (MAC) 2002, thatincludes a memory controller 2004 coupled to the external serial flashIC 2005 (serial flash memory), a SDRAM Controller 2006 coupled to theexternal SDRAM memory IC 2007, and an Ether MAC 2008 coupled to anexternal Ethernet PHY (physical) interface 2009 to provide data flowcontrol and multiplexing. The MAC 2002 is communicatively coupled to theGPIO 2010, the UART 2012, the timer 2014, the DMAC 2016, the INTC 2018,the ARM 2020, the physical layer of the OSI model (PHY) 2022, and theAFE 2024.

The HD-PLC Powerline Communications (PLC) IC (also referred to HD-PLC)supports fast megabit data rates over the filament or tether. HD-PLCcombines a high-frequency range (2 MHz to 28 MHz) with wavelet-basedorthogonal frequency-division multiplexing (OFDM) modulation to achievePHY speed up to 240 Mbps over powerline channels.

Powerlines, such as tethers and filaments, can be a hostile environmentfor communications. A lower 10 kHz to 500 kHz frequency region isespecially susceptible to interference, background noise, impulsivenoise, and group delays. HD-PLC applies advanced broadbandcommunications techniques such as orthogonal frequency divisionmultiplexing (OFDM) and forward error correction to provide robust datacommunication in the presence of narrowband interferers, group delays,jammer signals, impulsive noise, and frequency selective attenuations.It uses wider bandwidths at higher operating frequencies to achieve abetter channel for communication on powerlines.

FIGS. 15H-15K illustrate ground station electrical architecture diagramsassociated with the integrated spooler and base station 1001 describedin FIG. 9.

FIG. 15H illustrates electrical functions within the ground stationelectronics. The electronics are divided into three sub sections: apower subsection 2102, a communication and sensing subsection 2104, anda spooler function subsection 2106. The power subsection 2102 includesAC input filtering 2110, HV DC conversion 2111, 24 volt DC power bus2112, health-monitoring 2113, HV safety circuitry 2114, PFC 2115, 48volt bus for spooler function 2116, 12 volt DC power bus 2117, 5 volt DCpower bus 2118, and Ethernet interface 2119. The communication andsensing subsection 2104 includes AV Communications 2120, user input frompanel 2127, Ethernet switch 2122, health monitoring 2128, externalsensor input 2123, static dissipation 2129, local power conversion 2124,fan control 2130, fiber interface OCU 2125, power bridge 2131, and fiberinterface payload 2126. The spooler function subsection 2106 includes aBLDC motor controller 2132, tension control 2137, motor encoder 2133,brake interface 2138, heath monitoring 2134, spindle encoder 2139, jogbutton 2135, spooler bridge 2140, ground sensor board 2136, and filamentcooling 2141.

FIG. 15IA illustrates an electrical functional diagram for a groundstation 2100. The components of the diagram 2100 are described below.

Sensing circuitry 2101 is used to sense the AC current, voltage, andphase as well as the HV current and voltage. This data is used in healthmonitoring and logging, detecting faults during over voltage, undervoltage, over current, undercurrent, and power factor conditions.

The perforated line 2104 indicates a communication and sensingsubsection 2104. Data In/Out block 2105 is a differential serialinterface, such as Ethernet, differential SPI, or LVDS. Internal coolingfan(s) 2106 is mounted on the LCC transformer to cool the transformerand the leakage inductor. Another Internal cooling fan can be used tomove air within the electronics housing to help with cooling. A centralprocessing unit (CPU) 2102 for the ground station runs all softwarenecessary in the ground station. Also, software related interfaces andcalculations runs on the CPU 2102 outside of any processors insideperipheral ICs. Thermistor connections 2108 performs temperature sensingof important components within the electronics housing. A 7-port managedgigabit Ethernet switch 2110 with SGMII and RGMII/MH/RMII interfaces isfor advanced switching capabilities.

Small form-factor pluggable (SFP) module 2112 is for fiber opticconnection to Ethernet switch 2 110. This fiber optic connection can beused externally to send fiber optic to a user and/or to pass payloaddata from the air vehicle to the ground station switch. A rugged fiberoptic connector 2114 is mounted to the electronics housing meant forsending fiber to the user's OCU via a fiber cable. Rugged connectors2122 are mounted to the electronics housing and connect externalsensors. Each connector supplies 48 VDC at 3 A and Ethernet forcommunication. A ruggedized RJ45 connector 2120 is for system debugging,in field programming, and auxiliary use. FRAM memory IC block 2160 isfor general storage. An externally mounted 48V fan 2152 is for coolingthe baseplate.

Some embodiments may include a sensor board 2150 mounted externally (orinternally) and that interfaces to the electronics within the groundstation electronics housing. The sensor board 2150 may contain a GPS,barometric sensor, lightning sensor, magnetometer, EVIU, IR-Beacon, etc.The sensor board 2150 may contain sensors that provide data necessaryfor system stability and reliability, and may be added or changedwithout opening the electronics housing. MAC address 2162 is a networkaddress for the Ethernet and Wi-Fi.

The LEDs 2146 are for user indication of system status. AC Good LEDindicates status of AC power and HV primed/armed LED indicates if the HVis armed and ready to be enabled. The HV Good LED indicates the statusof the HV power bus and the fault LED indicates if there is a faultduring the operation of the system. Each LED 2146 may be individuallycontrolled, pulsed, blinked, etc. to communicate valuable information tothe users. The retract button is used to retract filament that has beenspooled out, in software there is a tension limit to determine if themotor should continue to spin. This keeps the filament from beingdamaged while retracting it.

The high voltage primer/arm switch 2145 is used as a safety mechanism inthe following manner: when the user wishes to put the Ground Station ina state where it is ready to receive the “HV Enable” command from theOCU or controlling device then the user holds this button for a durationof time until the HV Primed/Armed LED (2146) is illuminated. The LEDdoes not illuminate if system checks within software do not allow HVoperation. After the LED is illuminated the system is ready to receivethe “HV Enable” command.

The power switch 2144 for the system is used to apply or remove ACpower. An AC breaker 2142 is used to protect from over current events.This may or may not contain the power switch (2144). A rugged AC powerinput connector 2140 is rated for the full power and environmental rangeof the ground station.

FIG. 15IB illustrates an electrical functional diagram 2200 with IO. Theelectrical configuration of diagram 2200 reduces a footprint, weight andpower requirements for the integrated design of the station 1001. Thecomponents of the diagram 2200 are described below.

The triplexor 2202 combines and filters the communication signal and HVpower bus signal. The output is a power and communication signal sent tothe filament. Encoder 2209 is on the motor for the spool functionality.The encoder 2209 provides feedback for various control loops involvingthe spool motor. A spool motor 2208 is used to retract or spool outfilament.

A motor controller 2210 used to convert control signals to commutationsignals to the motor. An AZXBDC8 A8 or AZXDC15 A8 PWM servo drive isdesigned to drive brushless and brushed DC motors at a high switchingfrequency. To increase system reliability and to reduce cabling costs,the drive is designed for direct integration into a PCB. The drive isprotected against over-voltage, under-voltage, over-current, overheatingand short-circuits. A single digital output indicates operating status.The drive interfaces with digital controllers that have digital PWMoutput. The PWM IN duty cycle determines the output current and DIRinput determines the direction of rotation. This servo drive requiresonly a single unregulated isolated DC power supply, and is fully RoHS(Reduction of Hazardous Substances) compliant.

A secondary encoder 2211 is used for determining a position of the motorshaft. This provides feedback to the various ground station controlloops used for dynamic filament functionality, such as tension andvelocity.

Internal fan connections 2220 are used for cooling electronic componentswithin the electronics housing. A buzzer 2222 is used to alert users toissues.

Air vehicle communication signal 2204 is an output from either theDigital Filter board (2260) or the Megachips PLC module (2250), or anyother component that meets the requirements for filament communication.A digital filter board 2260 contains the electronics for Kintexcommunication, including the Kintex FPGA and analog front end along withsupporting peripheral electronics. The Kintex converts Ethernet to thefilament communication bus. A Megachips PLC Module 2250 is used toconvert Ethernet to the filament communication bus.

A further temperature sensor 2240 is used for internal temperaturesensing of electronic or mechanical components that require monitoringto ensure reliable operation such as heat sinks, MOSFETs, motors, coldplates, ambient air temperature etc.

Sensor ICs or circuits 2242, 2244 are used to sense voltage and currentof low voltage power buses within the system to ensure reliableoperation. A JTAG connection 2272 is used to program and debug theRenesas microcontroller 2102. A UART serial connection 2274 to theRenesas microcontroller 2102 is used for debugging of the ground stationsoftware. PCBA mounted LEDs 2276 are used for software development anddebug. Connector 2270 is used for fiber filament connection for payloaddata from the air vehicle.

FIG. 15IC is a triplexor 2290, such as triplexor 2202 shown in FIG.151B. The triplexor combines and filters the communication signal 2292and HV power bus 2294. The output is a power and communication signal2296 transmitted through one or more wires of the filament. Thetriplexor can be a passive device that provides frequency domainmultiplexing onto the filament conductors.

FIG. 15J illustrate a spooler system block diagram 2300 illustratingspooler functionalities to be implemented in the ground station. Aspooler board 2302 includes a PIC microcontroller 2308 and an AMC motordriver 2310. The spooler board 2302 is communicatively coupled to adevelopment tension and payout assemblies 2604. A spooler board 2302 isfurther communicatively coupled to a motor assembly 2306 that includes abrake 2320, a spindle encoder 2322, a brushless DC electric motor 2324,and a maxon encoder 2326. The spooler board 2302 is connected to a powersource 2312, a fan 2314, and an OCU 2316.

A temperature sensor 2340 is used for internal temperature sensing ofelectronic or mechanical components that require monitoring to ensurereliable operation such as heat sinks, MOSFETs, motors, cold plates,ambient air temperature etc.

A MOSFET switch 2319 on a PCBA is used for energizing the motor break. Amotor break engage switch 2318 is used to manually energize the motorbreak without need for software.

A tension/force sensor 2350 provides a direct measurement of the tensionon the filament. An encoder 2352 provides feedback of the position ofthe spooler motor. An encoder 2354 provides feedback of the amount offilament payed out by mounting to the motor shaft. In this embodiment, asingle board computer 2311 is used for Ethernet and serial conversion aswell and data logging and network interfacing.

FIG. 15K illustrates a base station electronics system diagram 2400. Thespooler and base station 1001 includes the ground system electronics2402 with the combined spooler and base station functionality. Theground system electronics 2402 provides power to, and receives datafrom, fans 2420, spooler motors 2422, spooler sensors 2424, and lightingsensors 2426.

The ground system electronics 2402 receives high voltage from the HVpower system 2404. The ground system electronics 2402 provides highvoltage and communication 2406 with the UAV. Further system input/output2408 include Ethernet or fiber communication with a system of the UAVand a stop function and a primer function.

The base station electronics system diagram 2400 further includes auniversal AC power switch, connector and breaker 2409, a universal ACinput filter 2407 for EM/EMC testing and concerns, and a DC-DC converter2405 used for all low voltage power buses needed by the ground stationelectronics. Port(s) 2442 are able to supply power and communication toexternal sensors.

A module 2440 can be installed in the ground station, or plugged inexternally, that provides functionality necessary for vehicle mountedlaunch functionality. This may include an Ethernet switch, RTK GPS, orother sensors similar to the SBS board 2150.

FIG. 15L is a method for externally programming a base station and/or anair vehicle to adapt the base station and/or the air vehicle todifferent applications or functions. A user is able to reset operationalfunctions of the base station and/or the air vehicle to adept the basestation and/or the air vehicle to different applications. Storedparameter values may be used to configure the base station and/or theair vehicle. For example, a user may externally reprogram the basestation and/or air vehicle to function as a surveillance vehicle, a celltower, or another commercial application.

At 2502, the method includes operating a computing device to interfacewith base station system to adjust program viable operating parametersof the base station and/or an air vehicle. At 2504, the method includestransmitting adjusted parameter values to a base station processorconnected to a controller chip. At 2506, the method includes storingchanged parameter values in base station memory where the functionalityof the base station and/or air vehicle is changed (such as bandwidthfilter allocation, payload operation, communicate protocols, and tetherconfiguration). At 2508, the method includes monitoring base station andair vehicle operation with one or more sensors. At 2510, the methodincludes further adjusting base station and/or air vehicle operation inresponse to system sensor data.

A user uses an OCU (e.g., a computing device) to reprogram the basestation and/or air vehicle. Reprogrammable functions include, but arenot limited to, changing a function of the spooler, changing a functionof the air vehicle, changing a function of the base station, changing abandwidth, changing spooler control loops, base station memory,resetting communications, switching payloads, and resetting operatingbandwidth filters. In an exemplary embodiment, the OCU is coupled viaEthernet to a microcontroller. The microcontroller is communicativelycoupled to a Megachip.

FIG. 15M is an exemplary control system 5920 for a UAV operating as acell tower. A control system 5940 is for a remote aerial vehicle inwhich one or more antennas 5924 receives incoming voice, data and/orvideo from a mobile device such as a cellphone. A remote radio head 5944configured to receive and transmit cellular communications in accordancewith known standards, including the Open Base Station ArchitectureInitiative (OBSAI), the Common Public Radio Interface (CPRI) standard,the European Telecommunications Standard Institute (ETSI), or any othernational, regional or industry based operating standard. In the presentembodiment, the remote radio head delivers data to the processor 5946which can use dedicated memory and processor elements to deliver thedata at transfer rates in a range up to 1 gigabyte per second or more.Line encoding at Ethernet transmission rates of 10 Gbps or more can beused. One or more optical transceivers 5948 such as the Datacom XFPoptical transceiver available from Finisar Corporation (Sunnyvale,Calif.) can be used for data transmission and reception onboard theaerial vehicle. The transmitter system can use an optional multiplexerdevice 5949 or other suitable switching circuitry to provide routing ofmultiple channels of data into the one or more optical fibers 5952 thatcarry the data to the base station using filament 5954. Optionally thesystem can use optical fiber to deliver data directly from the antennato the base station using systems available from Amphenol Aerospacelocated in Sidney, N.Y.

In one embodiment, CPRI may be provided on the aerial vehicle betweenthe one or more antennas 5901 and the one or more RRHs 5905. A CPRIinterface at the air vehicle enables seamless integration into nextgeneration carrier networks.

CPRI is a synchronous, Constant Bit Rate (CBR) serial protocol thattransports sampled radio interface data representing radio waveforms. Ithas strict latency, delay variation, and loss requirements and istypically transported from RRHs to Baseband Units (BBUs) oversynchronous networks via path switching (e.g. over provisioned paths).Paths may be formed using any technology that meets the CPRIrequirements (e.g. Sonet/SDH, Optical Transport Network (OTN),Asynchronous Transfer Mode (ATM) Virtual Circuits (VCs) and VirtualPaths (VPs), etc.). In a path switched operational model, multiple CPRIdata flows are combined onto paths using Time Division Multiplexing(TDM). Additionally, packet switched networks (e.g. Ethernet) can beused to carry CPRI as long as the CPRI requirements are met. Thisapproach requires mapping and demapping functions at the network edge(e.g. CPRI to Ethernet and Ethernet to CPRI) as well as jitter buffering(i.e. in the Ethernet to CPRI conversion). If multiple traffic classesare carried over Ethernet, strict prioritization of traffic classes atthe Ethernet layer is necessary.

Eight CPRI Signals have been defined in the CPRI specification V6.0,each supporting progressively higher bit rates. The signal beingtransmitted from the aerial vehicle to the base station should meetcertain latency and jitter requirements. In one embodiment, one waylatency between the antenna and the compute infrastructure (e.g. a BBUPool) must be less than 100 us and the maximum jitter (delay variation)is 65 ns. Delay variation can be compensated for using jitter buffers(i.e. adding latency) as long as the total one way latency does notexceed 100 us.

The one or more antennas 5901 on an aerial vehicle being used as a celltower may take a number of forms. For example, the aerial vehicle mayinclude one or more omnidirectional antennas. Omnidirectional antennashave a uniform radiation pattern, transmitting and receiving signals inall directions. Omnidirectional antennas place minimal navigationalrequirements on an aerial vehicle due to their uniform radiationpattern. Higher altitudes generally increase effective gain whereasparameters such as yaw, pitch, and roll have relatively little effect oncoverage of an omnidirectional antenna. Alternatively, the aerialvehicle may be equipped with one or more sectorized antennas. Sectorizedantennas have a directional radiation pattern and are combined to coveran area. For example, the aerial vehicle may deploy three sectorizedantennas each covering 120°. Similarly, the aerial vehicle may deployfour sectorized antennas each covering 90°. Likewise, the aerial vehiclemay deploy six sectorized antennas each covering 60°. Sectorizedantennas may require the aerial vehicle to maintain a heading andcontrol altitude, yaw, pitch, and roll or risk reduced service areacoverage or creation outages. Higher gain antennas (i.e. those withnarrow sectors) have radiation patterns (both horizontal and vertical)that are non-uniform (by definition) and, depending on the payloaddesign and network design, may require sectors to maintain a fixedlocation.

The aerial vehicle may transmit the communication data received by theantennas 5901 to a carrier network via a tether. As noted the tether maybe optical or electrical based. In one embodiment, a CPRI Physical Layer(Layer 1) can be implemented with electrical or optical components butLinks must have a Bit Error Rate (BER)<10⁻¹². The tether may be linkedto a triplexer circuit 5956 which routes the high voltage DC signal tothe DCDC converter 5958 which regulates power to the payload 5960, theparachute deployment circuit 5962, and the system processor 5946.

As noted, an optical tether can be composed of single mode or multimodefiber and can contain one or more fibers and/or fiber pairs. Wavedivision multiplexing may be used over a fiber to increase available bitrates as well as provide bi-directional data flows. To support the useof the CPRI interface, the optical fibers meets the BER,timing/synchronization, delay variation, and latency requirementsoutlined in CPRI Specification V6.0.

The CPRI Specification V6.0 does not specify the electrical cablingrequired to support a CPRI interface for electrical-based tethers.Specifically, the cabling is left up to the implementation and thus canbe the vehicle tether (as long as BER, timing/synchronization, delayvariation, and latency requirements are met, see CPRI SpecificationV6.0).

In another embodiment, while not a physical tether, a wireless link canbe used as the communications medium as long as it meets the BER,timing/synchronization, delay variation, and latency requirementsoutlined in CPRI Specification V6.0. For example, rather than transmitnetwork traffic over a twisted pair filament, or in addition to suchtraffic, a wireless RF transmitter/radio from the ground station isconnected to a RF receiver on the air vehicle. These radios can beconnected via hardware and software to the flightnetwork.

FIG. 15N illustrates vehicle-side integration using a MegaChip ICcontroller module 3502.

The Kintex FPGA 3508 implementation of communication is apurpose-specific implementation. Previous FPGA communications designrequired the FGPA to be reprogrammed to change the communicationsbehavior. The FPGA can be viewed as a block that converts Ethernetnetwork traffic to a communication protocol and bus that can betransmitted over a twisted pair interface.

The MegaChips (IC controller) communications approach providesoff-the-shelf availability, higher bandwidth capability, and betteradaptability. The IC controller detects the power line channelcharacteristics and determines the preferred rate. It also includeserror correction and selective transmission retry. These featuresprovide robust performance across a range of transmission line lengthsand qualities. This flexibility provides a system that can be adaptedfor a wide range of mission, vehicle, and tether configurations. Theachievable data rate is dependent on the tether gage and length. Thesefactors in turn impact the maximum flight altitude and payload weightcapacity. A vehicle and mission configuration capability leverages thiscommunications flexibility. The configuration presets allow the user toevaluate and choose compatible selections of payload weight, tetherlength and gage, and data rates.

The IC controller system also provides an indicator of communicationserrors. This signal can be used to dynamically adjust the bandwidthallocations on the air vehicle and adjust the payload data quality ordata package selection.

The IC control system ability to senses and adjusts to the optimal datarate and also improves the ability of the system to adapt to changes inthe filament characteristics due to manufacturing variability,degradation from normal wear and tear, and kinks in the filament. Thisextends the effective useful lifetime of a filament.

Payload data 3504 is received and routed by Ethernet switch 3506 to theIC controller module 3502 or the Kintex 3508 depending on payload sizeand bandwidth allocation. The module 3502 connects to a switch 3510 orCPU through a Mil interface. A triplexer 3512 or filter interface modulegets signals onto a common line, is shown in FIG. 151B in connectionwith the base station coupling to the tether. The Kintex 3502 routes thedata packets to the flight control system (referred to as torpedo)and/or the triplexer 3512 via an analog front end 3514.

In some embodiments, payload data 3516 routes to a secondary switch 3518with an optical interface for a fiber filament connection 3520 for afiber filament. The fiber filament connects to a ground user. Thesecondary switch 3518 may also include a fiber enabled payloadconnection. The electro-optical coupling into one or more optical fibersare described previously in connection with FIG. 15M. The UAV can use aradio payload or separate wireless transceiver as described previouslyfor a further means for data transmission and reception.

This approach is compatible with alternate Powerline Communication (PLC)modules that are compliant with IEEE 1901 (or other suitable standards)and provide adequate communications bandwidth to support the aerialsensing mission, such as the BCM60321 200 MBPS Intelligent Multi-PhySwitch. A preferred implementation uses aMegaChips controller because ofthe high levels of noise rejection with longer and higher gagemicrofilaments.

FIG. 15O is a mission configuration logical flowchart. At 3522, a userinputs planned payload weight, flight altitude during vehicleconfiguration, and mission planning. At 3524, the system determines asubset of viable potential tether configurations from the set ofavailable tethers (i.e., length, wire gage) that support the plannedmission payload and altitude. If there is no viable solution, the useris returned to 3522 to select acceptable options. At 3526, the systemcomputes the estimated bandwidth available for the set of viablepotential tethers and displays tether options and estimated bandwidth tothe user. Note that a look-up table can be used to store designatedparameter combinations suitable for desired payload and flightoperations. If there is no adequate solution, the user is returned to3402. At 3528, the user selects a configuration.

FIG. 15P1 is an exemplary mission configuration screen 3530. The screen3530 includes options for configuring a mission for an aerial vehicle.The options include, for example, selecting planned maximum flightaltitude 3532, selecting payloads 3533 (e.g., camera(s), radar(s), andradio(s)) to calculate weight of the payloads, and selecting tetherlength, bandwidth, and/or data rates 3534. Alternative screens mayinclude different or additional options. The screen can display presetcombinations of parameters that are preselected to automate selection ofdifferent flight modes.

FIG. 15P2 is an exemplary user interface 3535 to support a selectedmission. The user interface 3535 includes touch activated windows 3536,3537, and 3538. Touch activated window 3536 includes an indicator of airvehicle control. Touch activated window 3537 includes an indicator of atether length. Touch activated window 3538 includes an indicator of aspooler rate. Window 3539 displays an overhead view of the aerialvehicle relative to a vehicle-mounted ground station in an “On The Move”(OTM) mode, along with a relative altitude and a safe speed indicator.

The aerial vehicle can be used in a static hover to provide persistentsurveillance, or in the OTM mode where the aerial vehicle tracks thevehicle-mounted ground station. In the general sense, the static usageis a special case of the dynamic OTM mode. However, there are settingsand configurations as well as user interfaces that support a selectedmission. Four areas are used to support a selected mission: vehiclecontrol algorithm, vehicle state estimation algorithm, tether selection,and user feedback.

Vehicle control algorithm: In an OTM situation, the vehicle controlalgorithms command the aerial vehicle to tightly hold to a specifiedposition. The controller must retain some margin to respond tounpredictable environmental disturbances, such as wind. These marginsmay reduce a maximum allowable altitude and/or payload weight.Alternately, for a static hover mission, an operator may find itacceptable for the aerial vehicle to have a larger positional erroraround a target location in order to operate at a higher altitude orwith a higher payload weight. As shown in FIG. 15P1, multiple controllerpresets enable the operator to configure the aerial vehicle controlbehavior to suit the current mission. For example, the DC voltagetransmitted to the UAV may include a look-up table based on the payloadweight, vehicle geometry, flight altitude, etc., to provide settings andconfigurations to support the selected mission.

Vehicle state estimation algorithm: The vehicle state estimationalgorithms use data from available sensors to estimate the aerialvehicle position, velocity, and attitude, as well as other enablingparameters. The estimation algorithms use a vehicle dynamics model topropagate the estimated vehicle position between sensor measurementupdates. Having an accurate vehicle dynamics model improves the stateestimate, which in turn improves the ability of the aerial vehicle totrack the commanded position. Different dynamics model presets may beused to represent the static and OTM vehicle dynamics. For example, thevehicle state estimation algorithm may include a look-up table based onthe payload weight, vehicle geometry, flight altitude, etc., to providesettings and configurations to support the selected mission.

Tether selection: Some OTM users may choose to use a heavier, moredurable tether to provide robustness in case the tether grazes or snagson a structure or tree. While the ground vehicle from which the UAV islaunched traverses an area with potential UAV or tether obstructions.Increasing tether robustness via a thicker gage wire and/or thickerKevlar shrouding increases the tether weight and impact the maximumaltitude and forward speed. The mission configuration capability asshown in FIG. 15P1 accommodates this kind of selectable configuration.

User feedback: In the OTM operation, the ground launch vehicle speed islimited by the ability of the aerial vehicle to keep up. There are threeimportant components: whether the air vehicle can achieve sufficientspeed to keep within a specified horizontal distance from the groundvehicle, whether the length of unspooled tether is nearing the maximum,and whether the spooler can unspool or re-spool the tether at anadequate rate. If these maximums are exceeded, the ground vehicle maydisrupt the aerial vehicle flight, drag the aerial vehicle, or cause thetether to drag on the ground. These limits are affected by aerialvehicle capability and configuration, ground vehicle speed, and windspeed. The user has one primary response available when these limits arebeing reached—to slow the ground vehicle speed to allow the aerialvehicle to catch up. Thus, the latency of control signal and sensorsignal transmission rates must be within an operational range for agiven ground speed and air speed.

As shown in FIG. 15P2, the user interface 3535 displays information toprovide the user situational awareness of where the aerial vehicle isrelative to the ground vehicle, and status information on how close thesystem is to reaching these limits. A primary driving aid provides anoverhead view of the aerial vehicle position, relative to avehicle-forward frame of reference. This provides a more intuitive senseof the aerial vehicle position than a “North-Up” map. A bounding circlethat illustrates the desired position of the aerial vehicle is overlaidon top of the ground vehicle. This center circle may be commanded to beoffset from the center of the ground vehicle. The diameter of thebounding circle may dynamically adjust with aerial vehicle altitude. Aseries of fading breadcrumbs (position markers) can illustrate therecent position history of the aerial vehicle to provide a sense ofwhether the aerial vehicle position is getting better or worse. Acomposite indicator combines the metrics from the aerial vehiclecontrol, the tether length, and the spooler rate to provide an immediateeasy-to-understand directive to whether the ground vehicle is at a safespeed or whether the ground vehicle should slow down. In addition to thecomposite indicator, the user interface may also flash or create anauditory or haptic alert to notify the user that the aerial vehicle isnearing or exceeding the flight envelope limits. Supplementary displaysprovide the flight envelope details to help the vehicle operatorunderstand what is driving the composite indicator caution response. Thelaunch vehicle may also have an obstacle sensing network to detect anddisplay obstacles within a flight path envelope above the launchvehicle.

In some cases, the ground vehicle may be an autonomous vehicle. In thiscase, the flight envelope information can be transmitted digitally tothe autonomous ground vehicle to allow it to update its planned path.Situational awareness displays can also be available to human operators.

FIGS. 15Q-15S illustrate how different system configurations,specifically how the AV and ground system interact with differentfilament/communication configurations. These configurations do notassume a stationary ground system or user. These configurations remaintrue if the aerial vehicle was in a mobile or stationary configuration,i.e. on a boat, or ground vehicle.

FIG. 15Q illustrates a preferred configuration 3540. In thisconfiguration, the aerial vehicle 3541 is powered and communicatesthrough the micro-filament from the ground system 3542 to the airvehicle. Payload, telemetry, and control data passes through themicro-filament. An operator control unit 3543 is in communication withthe ground system 3542.

FIG. 15R illustrates a hybrid filament configuration 3545. In thisconfiguration 3545, the filament consists of both a copper pair as wellas a single or multi-fiber member. In this case the copper may or maynot be a twisted pair depending on whether communication is necessary onthe filament. The air vehicle 3546 can be powered via the copper wireinterface. Communication either only from the payload, or from both thepayload and air vehicle 3546 computer passes to and from the groundsystem 3547 via the fiber member(s). In some cases it may be necessary,due to network/data constraints, for data to pass from the payloaddirectly to a data management system used for high speed and/or highbandwidth data in this configuration. In this case external hardware canbe connected via a fiber port to the ground system 3547 allowing thisdata to pass directly from the payload light emitter and the opticalfiber. The ground station 3547 may be connected to an operator controlunit 3548 and a fiber data management unit 3549.

FIG. 15S illustrates a filament and wireless configuration 3550. In somecases it may be valuable to have power and/or data to pass via thecopper and/or hybrid filament as well as data streamed via a wirelesscommunication path to and from the air vehicle 3551. In this case an RFtransceiver is mounted on the ground system 3552 components as well asthe air vehicle 3551 to create a wireless link. This configuration mayallow bidirectional wireless communication or unidirectional dependingon the application. The wireless transceiver system can be configuredfor fully encrypted digital transmission for secure communications.

The system described herein can provide a plurality of communicationmodes simultaneously such as by wire, optical fiber, and/or wirelessformats as needed for specific payload configuration and application. Insome embodiments, the aerial vehicle may switch between communicationmodes, such as switching between fiber and tether wire, based on a typeof payload being transmitted. Some payloads, such as a high definitioncamera or software defined radio, may cause the downlink data rate fromthe aerial vehicle to the ground to be significantly larger than theuplink data from the ground to the aerial vehicle. If an optical fiberis available, the high-bandwidth payload communications is shifted tothe fiber. The copper communications can continue to be used for airvehicle control and telemetry. As different payloads are installed onthe aerial vehicle or the payloads are configured to change the datarate, a communications control integrated circuit (such as the Megachipssystem described herein) module dynamically adjusts the communicationslink.

The aerial vehicle can include an onboard control integrated circuitthat enables manual and/or automatic selecting of operating parametersfor different payload configurations, and different communication andpower utilization configuration to configure aerial vehicle fordifferent tasks. For example, in the manual configuration, an OCUdisplay graphical interface may include pull down menus allowingselection of presets for different operating modes. The ground stationparameters can also have presets corresponding to these modes. In someembodiments, different payloads may have different presets. For example,where the aerial vehicle acts as a cell tower replacement and transmitsinternet data, the aerial vehicle may be associated with first presetsassociated with high-bandwidth payload communications. The aerialvehicle may then switch to an observational platform and transmit cameradata, at which point the aerial vehicle may switch to second presetsassociated with camera data transmission. At another point, the aerialvehicle may experience GPS-denied, at which point the aerial vehicle mayswitch to third presets associated with positioning data transmission.The presets may be associated with particular configurations. Forexample, some configurations require higher bandwidth payloads (such as3G/4G and high resolution camera data transmission) while someconfigurations may emphasize power management (such as during low-powersituations or on-board battery operation) or positioning (such as duringGPS-denied flight).

As illustrated in FIGS. 15P1 and 15P2, the configuration presets allowthe user to evaluate and choose compatible selections of payload weight,tether length and gage, and data rates. The OCU can display presetcombinations of stored parameters that are preselected to automateselection of different flight modes. Stored parameters may include, butare not limited to, payloads, payload weight, vehicle geometry, flightaltitude, tether length, bandwidth, spooler rate, voltage, and datarates. Stored parameters may be used to configure the base stationand/or the air vehicle. For example, using the preset combinations, auser may reprogram the base station and/or air vehicle to function as asurveillance vehicle, a cell tower, or another application. Theparameter values are stored in the base station memory and/or the aerialvehicle memory where the functionality of the base station and/or airvehicle is changed based on the stored parameters (such as bandwidthfilter allocation, payload operation, communicate protocols, and tetherconfiguration).

When the aerial vehicle tracks a vehicle-mounted ground station in an“On The Move” (OTM) mode, there are preset configurations and parametersthat support the OTM mode. Multiple presets can configure the aerialvehicle control behavior to suit a particular mission (surveillance,cell tower, etc.). For example, the presets may reduce a maximumallowable altitude and/or payload weight, control the DC voltagetransmitted to the aerial vehicle, hold the aerial vehicle to aspecified position, and/or control the speed of the aerial vehicle.

In some embodiments, the aerial vehicle may act as a cell towerreplacement and may support a number of payload and network interfaces.A number of operational presets may be employed by the aerial vehicle totransmit the communication data to and from the antennas.

FIG. 15T illustrates a second illustration of a control and/orcommunications systems chip 5000 for the spooler and base station 1001.In an exemplary embodiment, the chip 5000 is a KHN13200 chip. TheKHN13200 is an IEEE 1901 compliant single chip HD-PLC PowerlineCommunications (PLC) IC. It provides a small form factor, highperformance, and operates on low power.

The chip 5000 includes a complete implementation of IEEE 1901, baseband5002, HD-PLC MAC/PHY 501O, SDRAM, and a fully integrated Analog FrontEnd (AFE) 5004 with high precision data converters and programmable gainamplifiers (PGA) 5006 to deliver fast, bidirectional communication overthe filament.

FIG. 15U illustrates a preferred embodiment of a High Voltage-LowVoltage converter 3555. The convertor 3555 employs a resonant converter(DC/DC) 3557 coupled to a rectification and filtering circuit 3559. Inthe exemplary embodiment, the converter 3557 receives 390 volts DC (VDC)from a power factor correction (PFC) converter. The circuit 3559transmits 1070 VDC to the aerial vehicle. A DC to low voltage (LV) busconverter 3560 receives the VDC from the PFC converter, and transmitsthe voltage to peripheral electronics and control systems.

Referring to FIG. 16, an aerial vehicle system includes an aerialvehicle 1607, which is connected to ground-based equipment. Thisequipment includes a robotic spooler 1603, which manages the filament; abase station 1602, which converts AC to DC voltage, and acts as thevehicle's communications hub, and a generator 1601 or line power source.The aerial vehicle 1607 includes a body 1604 with a number of struts1605 extending therefrom. Each strut 1605 has a thruster (e.g., apropeller coupled to a motor) disposed at its distal end. The body 1604houses on-board circuitry such as power conversion circuitry, vehiclecontrol circuitry, and sensor circuitry. The base station 1602 providespower (e.g., DC power) to the aerial vehicle 1607 over the filament 1606for powering the on-board circuitry and the thrusters.

Referring to FIG. 17A, in some vehicle use scenarios, the on-boardcircuitry includes two power buses (1730 and 1608). The high powerY-Board 1724 handles high voltage, receiving DC power from the DC/DCconverter 1720, and ultimately from the high voltage microfilamenttether 1707. It provides power to the motors 1734 of an aerial vehicleover the high power bus 1608, if any other vehicle subsystems requireshigh voltage power, it would supply them, too.

A second, lower voltage power Y-Board 1726 receives voltage from thebattery 1722, and passes it over the low power bus 1730 initiating thecontrol 1728, which switches ON the DC/DC converter 1720—effectivelypowering up the vehicle on commanded start, using power from the batterysystem. The lower power Y-Board 1726 via the low power bus 1730 alsoprovides power to the vehicle system electronics sub-systems which havelower power requirements than the motors. Some examples of thesesub-systems of the aerial vehicle that receive power from the low powerY-Board 1726 include the vehicle's system electronics 1732 which in turninclude both vehicle controls and, on-board sensors.

In addition to its primary mode of operation, outlined above, the highpower Y-Board 1724 performs a secondary function—that of supplementingor supplanting battery power to the motors 1734, if DC power from thefilament 1707 either is insufficient to meet demand, or fails.

Referring to both FIGS. 17A and 17B, the Y-Boards include switchingcircuitry 1708. The DC/DC power source (1703 and 1720) receives DC powerfrom the microfilament tether (1707); the DC power being associated witha tether voltage (e.g., 1000 Volts) and converts the DC power to a lowerDC voltage (e.g., 24 Volts) for use by the motors 1734. The DC/DC powersource 1703 connects to the switching circuitry 1708 which operates in anumber of modes to regulate the power provided to the vehicle bus (VBUS,1711) that powers the motors 1734. In some modes of operation, theswitching circuitry 1708 draws power from one or both of the battery1702 and the DC/DC converter 1703 to provide the drawn power for themotors 1734.

Referring to FIG. 17B, the battery 1702, the DC/DC converter 1703, andthe charger 1706 are external to the Y-Board itself. The battery powerswitching section 1709 includes a battery controller 1701 a, andparallel configuration of a switch 1740 a and a forward voltage diode1705 a. The DC/DC power switching section 1710 includes a DC/DC powercontroller 1701 b, and parallel configuration of a switch 1740 b and aforward voltage diode 1705 b. Both the battery power switching section1709 and the DC power switching section 1710 provide power to the VBUS1711.

In some examples, current in the circuit is directed using specializedintegrated circuit silicon chips, which contain comparators, and gatedriving charge pumps. The components are selected and qualified tohandle predetermined load and physical requirements, and assembled asshown in the circuit. In general, the Y-Board configuration—especiallythe high voltage Y-Board 1724 is an uncommon use for these components,which were designed for a different, lower demand, and less complex typeof switching.

I. Battery Startup Mode

A first mode of operation, referred to as battery startup mode, occurswhen the system electronics 1732 of the aerial vehicle are powered-on,prior to DC power being provided via the filament 1707. In this mode,the battery (1722 and 1702) provides the voltage, and the DC/DC (1707)does not provide a voltage. In this case, the battery charger (1706) isnot activated. Power flows from the battery 1722 to the low powerY-Board 1726. On the low power Y-board, a battery controller 1705 atriggers a switch 1740 a, powering the low power bus 1730 and in thegeneric Y-Board diagram, 1711). This is the initial state of the systemupon power-on.

II. DC/DC On Mode

A second mode of operation, referred to as DC/DC on mode, occurs whenoperating in Battery Startup Mode, after the initial power-on of theon-board circuitry 1728 and 1732, and when the DC/DC power source 1720begins providing voltage. In this mode, DC/DC 1720 provides a voltage tothe high power Y-Board 1724, which is provided to the high power bus1608 to enable the motors 1734. The DC/DC power source 1720 providespower to the charger 1706 via the high power Y-Board 1724. To transitionfrom the battery startup mode to the DC/DC On Mode, the DC/DC powercontroller 1701 b triggers switch 1740 b and the DC/DC power sourceprovides power to the high power bus (1608, and in the generic Y-Boardfigure, 1711). Once the VBUS (1608 and 1711) is powered, thebattery-side switch 1740 a is opened. In some examples, the diodecontrollers constantly monitor voltage sources. As soon as it sensesthat one of the sources is lower than another, the diode controllersswitch to connect to the higher voltage source. In some examples,comparators are used to make the determination.

During this time, the charger 1706 may or may not charge the battery1702 depending on the control and state of the system. In some examples,battery recharging occurs externally to the Y-Board. For example,battery recharging occurs when a dedicated battery processor on thepower distribution board detects low battery state. The chargerinitiates when it senses that Y-Bus can provide voltage higher than 22V. The maximum battery voltage is 21V.

In some examples, the Y-board utilizes a standardmetal-oxide-semiconductor field-effect transistor (MOSFET) component, bydesign, which includes a body diode. The time required to make thisdiode operational is in the order of nanoseconds. In operation, afterthe controller recognizes the presence of voltage, (in tens ofmicroseconds), it closes the main switch and reduces power dropping overthe body diode. This approach reduces the need for heat sinks—anotherkey element with major implications for use in aerial vehicles, whichface stringent weight constraints to meet their performance objectives.

III. Battery Power Mode

A third mode of operation of the switching circuitry 1708, referred toas battery power mode, occurs when operating in DC/DC On mode and theDC/DC power source 1703 lowers or stops providing voltage (e.g., thefilament is damaged or overloaded). To transition from the DC/DC On modeto the battery power mode, the diode 1705 a conducts as the voltage ofthe battery 1702 exceeds VBUS plus the forward voltage of the diode 1705a. The controller 1701 b switches the DC/DC switch 1740 b, disconnectingthe DC/DC 1703 from VBUS. Once VBUS is powered, battery side switch 1740a is triggered to conduct by the battery side controller 1701 a.

IV. DC/DC Power Mode

A fourth mode of operation of the switching circuitry 1708, referred toas the DC/DC power mode, occurs when operating in battery power mode andthe battery 1702 stops providing voltage (e.g., the battery is losingpower). To transition from the battery power mode to the DC/DC PowerMode, the DC/DC side diode 1705 b conducts as the voltage of the DC/DC1702 exceeds VBUS plus the forward voltage of the diode 1705 b. Thebattery side controller 1701 a triggers the switch 1740 a, disconnectingthe battery 1702 from VBUS. Once VBUS 1711 is powered, DC/DC side switch1740 b is triggered to conduct by its controller 1701 b.

In general, the Y-Board is configured to prevent power interruption. Ifpower is present from any of its multiple sources, it mediates thatpower, distributing it from the highest available source. Therefore, ifpower is accidentally or deliberately interrupted, the Y-Board sensesthe lack, and automatically switch to supply power from theuninterrupted source. If demand is such that power levels dip, theY-Board senses the lack and automatically switch to augment the lowlevel with power from the secondary source. Startup power management ishandled in the scenario described above, using two Y-Boards to firstdraw power to boot the vehicle from the battery in the absence of groundpower (the initial state), and then switch over to DC power via theDC/DC converter (and ultimately from the ground source via tether), oncethe power level from that source is sufficient.

In at least some examples, operation is controlled by a processorexecuting stored software in the vehicle, a ground-based processor, orboth. The software can be stored on a non-transitory machine readablemedium and including machine language or higher level languageinstructions that are processed.

In some examples, the diode based solution described herein isespecially effective for use in aerial vehicles since a capacitor-basedsolution would require a capacitor roughly the same size as the aerialvehicle, which would be impractical for flight.

FIG. 18 is an electronics and control schematic block diagram in anexemplary aerial vehicle (such as aerial vehicle 10 shown in FIG. 1) inan embodiment. In one embodiment, a microprocessor 1830 manages thecollection, scheduling, computation, transmission, and receipt of data.A serial link 1860, which may include a commercially available twistedpair transceiver integrated circuit, is capable of secure transmissionand receipt of data placed on the tether.

Voltage isolation may be facilitated by a variety of techniques known tothose of ordinary skill in the art having the benefit of thisdisclosure. In one embodiment, tuned magnetically isolated windings1861, 1862 reject all noise and frequencies that are not within adesired MBPS (megabits per second) data transmission packet range. Insome embodiments, voltage is isolated by capacitive isolation orelectro-optical isolation employing optical isolator integratedcircuits.

In one embodiment, one or more on-board data sensors may communicatewith the microprocessor 1830, as shown in FIG. 18. For example, agyroscope 1844 may continuously measure and integrate the angularrotation of the aerial vehicle. The gyroscope 1844 may include amicro-machined silicon integrated circuit. The microprocessor 1830 maycontinuously receive data from the gyroscope 1844 and may compute anddirect any correction to one or more of the electric motor controllers.The microprocessor 1830 may also use data from the gyroscope 1844 tocorrect angular drift by activating pitch servos 1845, yaw servos 1846,or a combination of both. The microprocessor 1830 may also control atether servo 1847 to wind and unwind the tether from the spool. Themicroprocessor 1830 and other control components may communicate viawireless signals when the tether is disconnected. Accordingly, in oneembodiment, the microprocessor and/or other control components orsensors described herein may include wireless controls or sensors, or awireless data receiver or transceiver interface.

In an embodiment, an optical imager digital signal processor (DSP)circuit 1840 may utilize built-in optical computational features of anoptical mouse data pointing chip. Utilizing a suitable lens combinationpointing toward the earth's surface, the optical imager DSP circuit 1840can update changes in physical position up to 6000 times per second. Forexample, the optical imager DSP 1840 may be a signal processing engine.

In one embodiment, the aerial vehicle may also include an altimeter1841. The altimeter 1841 allows the microprocessor to precisely holdaltitude, or to ascend or descend in a controlled manner. The altimeter1841 may facilitate, for example, traversing a stairwell ortransitioning between floors of a building.

In an embodiment, the aerial vehicle may have a global positioningsystem (GPS) module 1842 that can facilitate continuous monitoring ofthe position of the aerial vehicle. The microprocessor 1830 may act onthe positional data provided by the GPS module 1842 to allow the aerialvehicle to traverse particular paths. The GPS module 1842 may alsoreport back an actual GPS position of the aerial vehicle to the basestation (such as base station 30 shown in FIG. 1). In one embodiment,the GPS module 1842 includes a miniature GPS receiver. In oneembodiment, an accelerometer 1843 may continuously measure and integrateaccelerations in the three orthogonal physical planes of the aerialvehicle.

In an embodiment, the microprocessor 1830 may communicate with anobservation device or sensor such as, but not limited to, camera 1812 aswell as with a pan servo 1833, a tilt servo 1834 operating servomotors,and a zoom servo 1835. In certain configurations, the microprocessor1830, the optical imager DSP 1840, the altimeter 1841, the GPS module1842, the accelerometer 1843, and the gyroscope 1844 reside on a printedcircuit assembly 1850.

In one embodiment, a PARC system as described herein may be deployed toprovide a mobile and aerial cell tower. For example, as depicted in FIG.19A, an aerial vehicle (such as aerial vehicle 10 shown in FIG. 1) maybe equipped with one or more radio antennas 1901 and one or more remoteradio heads (RRHs) 1905. The antennas may establish communication withan individual's mobile device. In an exemplary embodiment, the aerialvehicle is equipped with three antennas 1901 and three RRHs 1905. In apreferred embodiment, the one or more RRHs 1905 connect to the basestation (such as base station 30 shown in FIG. 1 or FIGS. 13A-13U) usingan optical tether 1910 formed from a single mode or multi-mode fiberthat contains one or more optical fibers and/or fiber pairs. As anon-limiting example, the optical tether 1910 may be an ITU-TRecommendation G.652.D-compliant optical fiber with enhanced low-lossand bend fiber technologies such as a Corning® SMF-28® Ultra OpticalFiber. Wave division multiplexing may be used over a fiber to increaseavailable bit rates as well as provide bi-directional data flows. Aspreviously discussed, the optical tether may connect to spooler such asspooler 20 shown in FIG. 1) which may be communicatively and physicallycoupled to the base station, a DPA/MC (such as DPA/MC 40 shown in FIG.1), and an OCU (such as OCU 50 shown in FIG. 1). As discussed furtherbelow, an interface, such as a Common Public Radio Interface (CPRI) orother suitable interface may be provided onboard the aerial vehicle forconverting data into a suitable format over an optical fiber or otherphysical layer.

In one embodiment, base station may include carrier interface 1920 forconverting data received from the aerial vehicle, such as communicationdata from a cellular communication established between an individual andone or more of antennas 1901 on the aerial vehicle, into a suitable formfor transit on a carrier network. As further discussed herein, thecarrier interface 1920 may be a CPRI interface or other suitableinterface.

It should be appreciated, that although the discussion herein refers tothe preferable use of optical fibers for transmitting communication datafrom the aerial vehicle over the tether, other mediums may also be used.For example, in one embodiment, the one or more remote radio heads mayconnect via the tether to the base station using an electricalconnection in the tether composed of unshielded twisted pair (UTP)wires. In another embodiment, the communication data may be relayedwirelessly by the RRHs 1905 to the ground for communication to thecarrier network.

It should further be appreciated that the configuration depicted in FIG.19A is exemplary and made for the purpose of illustration and that theembodiments of the present invention are not limited to the specificallyillustrated configuration. For example, in one embodiment, instead ofthe aerial vehicle including the RRHs 1905, the RRHs may be located onthe ground and connect to the antennas on the aerial vehicle via anoptical tether or other connection. Similarly, different numbers ofantennas 1901 and RRHs 1905 may be deployed on the aerial vehiclewithout departing from the scope of the present invention.

FIG. 19B is an exemplary PARC system deploying multiples UAVs as celltowers in a networked environment. The multiple UAVs 1911 may utilize anoptical tether to communicate data to spoolers 1912 and base station1913. The base station 1913 may be coupled to RRHs 1914 providing aninterface to a carrier network 1915. Conventional cell towers 1916 mayalso be communicating with carrier network 1915 which may include BBUpool 1917. The UAVs 1911 may acquire partial communication data that iscombined on carrier network 1915.

FIG. 19C is an exemplary control system for a UAV operating as a celltower. For example, shown in FIG. 19C is a control system 1940 for aremote aerial vehicle in which one or more antennas 1924 receivesincoming voice, data and/or video from a mobile device such as acellphone. A remote radio head 1944 configured to receive and transmitcellular communications in accordance with known standards, includingthe Open Base Station Architecture Initiative (OBSAI), the Common PublicRadio Interface (CPRI) standard, the European TelecommunicationsStandard Institute (ETSI), or any other national, regional or industrybased operating standard. In the present embodiment, the remote radiohead delivers data to the processor 1946 which can use dedicated memoryand processor elements to deliver the data at transfer rates in a rangeup to 1 gigabyte per second or more. Line encoding at Ethernettransmission rates of 10 Gbps or more can be used. One or more opticaltransceivers 1948 such as the Datacom XFP optical transceiver availablefrom Finisar Corporation (Sunnyvale, Calif.) can be used for datatransmission and reception onboard the aerial vehicle. The transmittersystem can use an optional multiplexer device 1949 or other suitableswitching circuitry to provide routing of multiple channels of data intothe one or more optical fibers 1952 that carry the data to the basestation using filament 1954. Optionally the system can use optical fiberto deliver data directly from the antenna to the base station usingsystems available from Amphenol Aerospace located in Sidney, N.Y.

In one embodiment, CPRI may be provided on the aerial vehicle betweenthe one or more antennas 1901 and the one or more RRHs 1905. A CPRIinterface at the air vehicle enables seamless integration into nextgeneration carrier networks.

CPRI is a synchronous, Constant Bit Rate (CBR) serial protocol thattransports sampled radio interface data representing radio waveforms. Ithas strict latency, delay variation, and loss requirements and istypically transported from RRHs to Baseband Units (BBUs) oversynchronous networks via path switching (e.g. over provisioned paths).Paths may be formed using any technology that meets the CPRIrequirements (e.g. Sonet/SDH, Optical Transport Network (OTN),Asynchronous Transfer Mode (ATM) Virtual Circuits (VCs) and VirtualPaths (VPs), etc.). In a path switched operational model, multiple CPRIdata flows are combined onto paths using Time Division Multiplexing(TDM). Additionally, packet switched networks (e.g. Ethernet) can beused to carry CPRI as long as the CPRI requirements are met. Thisapproach requires mapping and demapping functions at the network edge(e.g. CPRI to Ethernet and Ethernet to CPRI) as well as jitter buffering(i.e. in the Ethernet to CPRI conversion). If multiple traffic classesare carried over Ethernet, strict prioritization of traffic classes atthe Ethernet layer is necessary.

Eight CPRI Signals have been defined in the CPRI specification V6.0,each supporting progressively higher bit rates.

CPRI CPRI Rate Signal (Gbit/s) Standard Line Coding CPRI-1 0.61440 8B/10 B line coding (1 × 491.52 × 10/8 Mbit/s) CPRI-2 1.22880 8 B/10 Bline coding (2 × 491.52 × 10/8 Mbit/s) CPRI-3 2.45760 8 B/10 B linecoding (4 × 491.52 × 10/8 Mbit/s) CPRI-4 3.07200 8 B/10 B line coding (5× 491.52 × 10/8 Mbit/s) CPRI-5 4.91520 8 B/10 B line coding (8 × 491.52× 10/8 Mbit/s) CPRI-6 6.14400 8 B/10 B line coding (10 × 491.52 × 10/8Mbit/s) CPRI-7 9.83040 8 B/10 B line coding (16 × 491.52 × 10/8 Mbit/s)CPRI-8 10.13760 64 B/66 B line coding (20 × 491.52 × 66/64 Mbit/s)

The signal being transmitted from the aerial vehicle to the base stationshould meet certain latency and jitter requirements. In one embodiment,one way latency between the antenna and the compute infrastructure (e.g.a BBU Pool) must be less than 100 us and the maximum jitter (delayvariation) is 65 ns. Delay variation can be compensated for using jitterbuffers (i.e. adding latency) as long as the total one way latency doesnot exceed 100 us.

The one or more antennas 1901 on an aerial vehicle being used as a celltower may take a number of forms. For example, the aerial vehicle mayinclude one or more omnidirectional antennas. Omnidirectional antennashave a uniform radiation pattern, transmitting and receiving signals inall directions. Omnidirectional antennas place minimal navigationalrequirements on an aerial vehicle due to their uniform radiationpattern. Higher altitudes generally increase effective gain whereasparameters such as yaw, pitch, and roll have relatively little effect oncoverage of an omnidirectional antenna. Alternatively, the aerialvehicle may be equipped with one or more sectorized antennas. Sectorizedantennas have a directional radiation pattern and are combined to coveran area. For example, the aerial vehicle may deploy three sectorizedantennas each covering 120°. Similarly, the aerial vehicle may deployfour sectorized antennas each covering 90°. Likewise, the aerial vehiclemay deploy six sectorized antennas each covering 60°. Sectorizedantennas may require the aerial vehicle to maintain a heading andcontrol altitude, yaw, pitch, and roll or risk reduced service areacoverage or creation outages. Higher gain antennas (i.e. those withnarrow sectors) have radiation patterns (both horizontal and vertical)that are non-uniform (by definition) and, depending on the payloaddesign and network design, may require sectors to maintain a fixedlocation.

The aerial vehicle may transmit the communication data received by theantennas 1901 to a carrier network via a tether. As noted the tether maybe optical or electrical based. In one embodiment, a CPRI Physical Layer(Layer 1) can be implemented with electrical or optical components butLinks must have a Bit Error Rate (BER)<10⁻¹². The tether may be linkedto a triplexer circuit 1956 which routes the high voltage DC signal tothe DCDC converter 1958 which regulates power to the payload 1960, theparachute deployment circuit 1962, and the system processor 1946.

The following table lists standard CPRI Physical Layer Modes:

Optical Line bit rate Electrical Short range Long range  614.4 Mbit/sE.6 OS.6 OL.6 1228.8 Mbit/s E.12 OS.12 OL.12 2457.6 Mbit/s E.24 OS.24OL.24 3072.0 Mbit/s E.30 OS.30 OL.30 4915.2 Mbit/s E.48 OS.48 OL.486144.0 Mbit/s E.60 OS.60 OL.60 9830.4 Mbit/s E.96 OS.96 OL.96 10137.6Mbit/s  E.99 OS.99 OL.99

As noted, an optical tether can be composed of single mode or multimodefiber and can contain one or more fibers and/or fiber pairs. Wavedivision multiplexing may be used over a fiber to increase available bitrates as well as provide bi-directional data flows. To support the useof the CPRI interface, the optical fibers meets the BER,timing/synchronization, delay variation, and latency requirementsoutlined in CPRI Specification V6.0.

The CPRI Specification V6.0 does not specify the electrical cablingrequired to support a CPRI interface for electrical-based tethers.Specifically, the cabling is left up to the implementation and thus canbe the vehicle tether (as long as BER, timing/synchronization, delayvariation, and latency requirements are met, see CPRI SpecificationV6.0).

In another embodiment, while not a physical tether, a wireless link canbe used as the communications medium as long as it meets the BER,timing/synchronization, delay variation, and latency requirementsoutlined in CPRI Specification V6.0.

FIG. 19D illustrates a filament 1970 comprising copper 1978 and fiber1980. The filament 1970 may be a fiber and copper twisted or untwistedpair. The filament 1970 includes an outer strength member jacket 1982.In an exemplary embodiment, jacket 1982 is made of the Kevlar element.The copper, dual fiber solution increases data throughput (bandwidth) ofthe filament, increases reliability of filament communications,decreases cost of the communications system, decreases size and weightof the communications system, and is able to support higher bandwidthpayloads (such as 3G/4G and high resolution camera data transmission).In an exemplary embodiment, the filament 1970 is longer than 550 feetand supports greater than 100 Mbps.

In an exemplary embodiment, the filament 1970 cable operates up to 150degrees Celsius with a maximum current over the filament of 1.7 A-2.8 A.Since resistance in a wire increases linearly with temperature, at somevalue, signal integrity and control of the UAV will degrade. Therefore,in some embodiments, the filament 1970 temperature is limited to apredefined desired maximum when drawing typical operational amperage.For example, on some embodiments, if the current exceeds a predefinedthreshold (e.g., 2.5 A) for a predefined amount of time (e.g., threeseconds) then the base station turns off the high voltage. As seen inFIG. 19E, the filament can comprise a twisted pair within thereinforcing sheath.

In some embodiments, one or more additional Aramid strength members areadded in the interstitial space to increase filament strength anddurability. The synthetic reinforcing fibers or members can alsocomprise composite materials. Para-aramid fibers, such as Kevlar and/orTwaron, provide the strength to weight ratio required. For spooling ofthe filament, fatigue, resistance and flexibility are also required.Composite aramid fibers, such as Kevlar 119 and 129 fibers or filamentsavailable from DuPont, Wilmington, Del. are suitable for theseembodiments. Shown in FIG. 19F, the other sheath of filament 1979provides insulation against ambient conditions. A single, centrallypositioned strength element 1987 can be used to reinforce the filament.Optionally, optical fibers 1989 can also be used for data communication,as described herein.

FIG. 20 depicts a block diagram of exemplary CPRI and Ethernetinterfaces that may be employed by an embodiment. The exemplary PARCsystem deploying a UAV as a cell tower replacement may support a numberof payload and network interfaces. Vehicle payloads may be presentedwith CPRI and Ethernet interfaces and those interfaces are connected(via the tether or wireless links) to CPRI and Ethernet carrier networkinterfaces. A number of operational modes may be employed by the aerialvehicle to transmit the communication data to and from the antennas.Included among these operational modes are the following fouroperational modes listed in the table below.

Mode Interface Type Description 00 CPRI CPRI Direct 01 CPRI CPRI overEthernet 10 Ethernet Ethernet Direct 11 Ethernet Ethernet over CPRI

Two of these modes are CPRI Direct (00) and Ethernet over CPRI (11).CPRI direct is the simplest operational mode transporting 8B/10B and64B/66B encoded serial data over electrical, optical, and wireless mediaas depicted in FIG. 21. Once CPRI Direct is available, Ethernet (andother Layer 2 protocols) may be implemented over CPRI.

Two other operation modes depicted in FIG. 22 are Ethernet Direct (10)and CPRI over Ethernet (01). Ethernet may be implemented directly overelectrical or optical tethers and wireless media.

Once Ethernet Direct is available CPRI may be implemented over Ethernet.In the case of CPRI over Ethernet, strict traffic prioritization andjitter buffering (at the Ethernet layer) should be used to meet the BER,delay variation, and latency requirements outlined by CPRI.

In one embodiment, IQ data is carried in CPRI Bit Streams that aremapped to Ethernet frames via a Mapping Function as depicted in FIG. 23.This mapping function defines the way the CPRI Bit Stream is placed inthe Ethernet frame. Ethernet frames are transmitted over Electrical,Optical, and Wireless media. Upon reception of Ethernet frames thoseframes are demapped to produce CPRI Bit Buffers (i.e. the CPRI contentsof each frame). These bit buffers are placed in a jitter buffer which isplayed out (with added latency) at the same bit rate as the originalCPRI bit stream. Frame slips (i.e. jitter buffer overrun and underrun)conditions are avoided through clock synchronization (i.e. clockfrequency synchronization) between the input bit stream and output bitstream.

In an embodiment, a tether/physical adaption layer is utilized. Thisgeneralized layer maps logical bit streams and frames to physical media(i.e. Layer 1 sublayers). In CPRI Direct and Ethernet over CPRI it iscomprised of the TDM/Circuit Emulation block and the mapping of thosetime slots/circuits to Electrical, Optical, and Wireless transceivers.In Ethernet Direct and CPRI over Ethernet the Physical Coding Sublayer(PCS), Physical Medium Attachment Sublayer (PMA), and Physical MediumDependent Sublayer (PMD) comprise the Tether/Phy Adaptation Layer.

In one embodiment, the physical interface layer is comprised ofElectrical, Optical, and Wireless interfaces and the modulation schemesused to transmit data.

In FIG. 24A, as illustrated, a number of physical or logical links canbe combined to create larger capacity logical links. This process iscalled Link Bonding. Combined links may have different capacities/bitrates. When this occurs data is proportionally split between the linksupon transmission. Received data is read from multiple links andreassembled before being presented as a single data flow from a singlelogical link.

In one embodiment, the exemplary PARC system deploying a UAV as a celltower may provide a communication link that utilizes CPSFK modulation totransport 250 byte packets over twisted pair wiring. These packets mayhave the following format

Offset Data 0 Packet Type/Source Lo 1 Packet Type/Source Hi 2 PacketSequence Number 3 Packet data size in bytes 4-248 Payload 249 CRC Hi 250CRC Loand may be prefaced by a 36 bit preamble followed by the packet's bitsas shown in the table below.

Preamble - Packet Packet Payload - CRC - 36 bits Type/Source - SequenceNumber - 1984 bits 16 bits 16 bits 8 bits

CPRI data streams can be mapped directly into these packets. Whencarrying CPRI, the Packet Type/Source is set to the CPRI assignednumber, as illustrated in FIG. 24B.

As discussed above, the aerial vehicle operating as cell tower mayemploy sectorized antennas. In such an embodiment, the ability tomaintain a steady position is important to prevent signal degradation.In one embodiment, the aerial vehicle may employ fixed rotor thrustvectoring such as described in a co-pending PCT application entitled“Fixed Rotor Thrust Vectoring”, filed Jun. 3, 2015, application numberPCT/US2015/033992 filed Jun. 3, 2015, the contents of which areincorporated herein by reference in their entirety. More particularly,as described therein, the aerial vehicle may employ a multi-rotorhelicopter control system.

FIG. 25A depicts a system 2500 that includes a base station 2502transmitting power, control, and/or communication signals through atether 2504 to an elevated transceiver module 2506. The ground stationincludes power management systems and control circuits. In an exemplaryembodiment, the elevated transceiver module 2506 may be equipped withantennas 2508, such as radio antennas, and function as a cell tower. Thesystem 2500 may include one or more convertors at the base station 2502and/or the elevated transceiver module 2506.

In an exemplary embodiment, the tether 2504 is a microfilament, a pairof threadlike wires that transmits power to the elevated transceivermodule 2506 while also enabling transmission of bi-directional data andhigh-definition video. In an exemplary embodiment, the transmitted poweris 800 volts-1200 volts direct current (DC). In one embodiment, themicro-filament tether 2504 may be Kevlar-jacketed twisted copper pairwith insulation that provides a power link and/or a communication linkbetween the base station 2502 and the elevated transceiver module 2506.As illustrated in FIGS. 25H-25I, multiple tethers 2504 can be housed ina single cable bundle to allow for ease of installation and reliability.

The base station 2502 is connected to the elevated transceiver module2506 via the tether 2504. The base station 2502 converts power tohigh-voltage (HV) power and provides HV power to the elevatedtransceiver module 2506. The base station 2502 includes an assembly thathouses an alternating current (AC) power input and high voltageconversion electronics in an environmentally sealed enclosure. In anexemplary embodiment, the base station 2502 receives 84 volts-264 voltsAC from an outside power source (e.g., a generator, power station,etc.). The base station 2502 includes an AC-DC convertor 2510 to convertthe received AC power to DC power for transmission through the tether2504. The base station 2502 also includes a high voltage output port tosupply high voltage via the tether 2504 to the elevated transceivermodule 2506.

The HV power is provided over the microfilament tether 2504 to theelevated transceiver module 2506 for use for energy intensive operationssuch as telecom. The elevated transceiver module 2506 includes a DC-DCconvertor 2512 that converts the received DC power from one voltagelevel to another before transmitting the power to the antennas 2508(e.g., radio antennas).

The microfilament may also provide a communication pathway used tocommunicate with the elevated transceiver module 2506 by an operator ofan operator control unit (OCU). The base station 2502 may furtherinclude a data platform adapter/media converter (DPA/MC) to serve thefunction of connecting the OCU to the base station 2502 while alsoproviding electrical shock hazard isolation. The DPA/MC may include anoptical port to connect to the base station 2502 via a fiber optic cableand may also include an Ethernet port to connect to the OCU. The OCU maybe a ruggedized laptop or other computing device equipped with and ableto execute the OCU application described further herein enablingmonitoring and/or control of the base station 2502 and/or voltage and/orthe elevated transceiver module 2506. The DPA/MC may communicate withthe base station 2502 over an optic fiber and communicate with the OCUover an Ethernet connection.

In an embodiment, the elevated transceiver module 2506 may include animaging device, radar or other sensor used to acquire data.

In some embodiments, the base station 2502 includes safety interlocks2514 that will immediately auto-shutoff power to the system. The autoshutoff utilizes ground shift detection and no connection detection. Thebase station 2502 may further include safe-turn on utilizing positiveconnect detection and a multi-stage lockout (primer). The safetyinterlocks 2514 are configured to shut down power when any serviceablesystem component is accessed.

In one embodiment, the system as described herein may be deployed toprovide a cell tower. For example, the elevated transceiver module 2506may include and/or be equipped with one or more radio antennas 2508 andone or more remote radio heads (RRHs). The antennas 2508 may establishcommunication with an individual's mobile device. In a preferredembodiment, the one or more RRHs connect to the base station 2502 usingan optical tether 2504 formed from a single mode or multi-mode fiberthat contains one or more optical fibers and/or fiber pairs. As anon-limiting example, the optical tether 2504 may be an ITU-TRecommendation G.652.D-compliant optical fiber with enhanced low-lossand bend fiber technologies such as a Corning® SMF-28® Ultra OpticalFiber. Wave division multiplexing may be used over a fiber to increaseavailable bit rates as well as provide bi-directional data flows. Aninterface, such as a Common Public Radio Interface (CPRI) or othersuitable interface may be provided for converting data into a suitableformat over an optical fiber or other physical layer.

It should further be appreciated that the configuration depicted in FIG.25A is exemplary and made for the purpose of illustration and that theembodiments of the present invention are not limited to the specificallyillustrated configuration. For example, in one embodiment, the RRHs maybe located on the ground and connect to the antennas 2508 on thetransceiver via an optical tether 2504 or other connection. Similarly,different numbers of antennas 2508 and RRHs may be deployed withoutdeparting from the scope of the present invention.

In one embodiment, there may be multiple apparatuses as cell towers in anetworked environment. The multiple apparatuses may utilize an opticaltether 2504 to communicate data to one or more base stations 2502. Thebase station 2502 may be coupled to RRHs providing an interface to acarrier network. Conventional cell towers may also be communicating withcarrier network which may include BBU pool. The apparatuses may acquirepartial communication data that is combined on carrier network.

In some embodiments, the ground station may utilized avoltage-controlled duty cycle to correct a drop in voltage. The tethercan generally transmit voltage of 300 volts or greater, and preferablyin the range of 500-1200 volts.

FIGS. 25B-25C illustrates a front and back view of a base station thatincludes a number of components and features. For example, the basestation may include a base station enclosure assembly 2501. The basestation enclosure assembly 2501 may house an AC power input and highvoltage conversion electronics in an environmentally sealed enclosure.Power and communications connection ports, and AC input switches may belocated in the rear panel. High voltage enable/disable controls andstatus indicators may be located in the top panel. A magnetic mount2501A may be used by the base station to provide a magnetic feature forsecuring an optional beacon assembly to the base station. A beacon I/Oport 2501B may provide a connector interface to the optional highvoltage beacon assembly. In one embodiment, a rubber sealing cap may beprovided for the port when the beacon is not present. The base stationmay be equipped with an HV primer indicator LED 2501C and an HV primerbutton 2501D. The HV primer indicator LED 2501C may be a colored LEDsuch as a red LED that indicates that high voltage is primed. The HVprimer button 2501D may be provided to enable/disable the high voltageoutput from the base station to the transceiver. As a non-limitingexample, the HV primer button 2501D may be configured so that a userpressing the button for >4 seconds enables or disables OCU control ofthe high voltage. An emergency ESTOP switch 2501E may be provided thatwill immediately terminate power to the system if depressed (presseddown) during operation. This button may also serve an arming function(i.e., it enables activation of the HV primer button) during thestart-up sequence. In one embodiment, if the ESTOP switch is depressedupon initial power up of base station, the base station will not powerup. The ESTOP switch 2501D may be provided in different forms includingas a two position red mushroom shaped button.

A number of LED indicators may be provided in the base station such as aHigh Voltage good indicator LED 2501F, an AC good indicator LED 2501Gand a fault indicator LED 2501H. The High Voltage good indicator LED mayindicate the status of high voltage output (e.g. if not illuminated thehigh voltage is not activated). The AC good indicator LED may indicatethe status of primary and/or secondary AC input from a grid/generatorsource (e.g.: if the LED is not illuminated, AC input is not activated).The fault indicator LED may indicate a system power fault condition(e.g.: if the LED is illuminated, high voltage is automaticallydisabled).

The base station may also include a number of ports, terminals andswitches. These may include an HV output port 25011, a GND lug/terminal2501J, an interface port 2501K, an Ethernet I/O port 2501L, an OpticalEthernet I/O port 2501M, a primary AC input port 2501N, a secondary ACinput port 2501O, an aux ac out output port 2501P, a primary AC switch2501Q, a secondary AC switch 2501R, and an Aux AC out switch 2501S. TheHV output port may supply high voltage (via the base station) to theelevated transceiver module 2506. The GND lug/terminal may provide anattachment point for system electrical grounding. The interface port maysupply power (low voltage to the elevated transceiver module 2506) andcommunication (via the base station to the elevated transceiver module2506) to the elevated transceiver module 2506. The Ethernet I/O port mayprovide a connector interface to the OCU or router/switch and may beused for debug or lab operations. The Ethernet I/O port may includeMIL-rated connector plugs attached via lanyard. The base station mayalso include an Optical Ethernet I/O port that provides a connectorinterface to Ethernet-fiber converter. This port may be used forconnection during normal operation. Optical Ethernet I/O port mayinclude MIL-rated connector plugs attached via lanyard. The primary ACinput port that provides a connector interface to a primary AC inputsource. The primary AC input port may include rated connector plugsattached via lanyard. The secondary AC input port may provide aconnector interface to a secondary AC input source. The secondary ACinput port may include rated connector plugs attached via lanyard. Theaux AC out output port may provide a connector interface to powerperipheral device (i.e., OCU). This port may include MIL rated connectorplugs attached via lanyard. It should be noted that voltage availablefrom AUX AC may be the same as voltage on the Primary AC/Secondary AC. Aprimary AC switch may be provided as a two position toggle switch thatturns AC input on and off. The secondary AC switch may also be providedthat turns AC input on and off. Similarly the Aux AC out switch may beprovided in the base station as a two position toggle switch that turnsaux AC output on and off.

The base station may also include heat sinks and/or fins 2501T andcooling fans 2501U. The heat sinks and fins may provide passive coolingof internal electronics and the cooling fans may provide cooling anddirected airflow for the internal electronics. An exemplary base stationmay also include a side plate assembly 2501V to house the cooling fansand heat sink fins that are integral to the base station enclosure.

The base station may include a high voltage beacon assembly 2501Wconfigured to provide a visual Indication (e.g.: flashing light) that isilluminated when high voltage is activated. The beacon usage is optionaland may be used at the discretion of the operator depending on lightdiscipline considerations. The beacon may incorporate a cable/plug thatinterfaces with a beacon port on the base station enclosure. The beaconmay be retained on the base station enclosure via an integral magnet.

In one embodiment, the base station may be configured to utilize anumber of different types of cables including but not limited to aprimary AC input cable, a secondary AC input cable, an Ethernet cableand an auxiliary AC output cable. As non-limiting examples, the primaryAC input cable may be a 3 meter (10 feet) sealed, shielded cable with anMIL-rated circular connector that interfaces with a grid or generatorpower source. The secondary AC input cable may be a 3 meter (10 feet)sealed, shielded cable with a MIL-rated circular connector. Thesecondary AC input cable is optional and interfaces with a grid orgenerator power source. The connector termination may becustomer-specific. The Ethernet cable is an optional 3 meter (10 feet)Ethernet cable with RJ-45. The Ethernet cable provides a connection froma base station Ethernet port to an Ethernet port on a peripheral device(e.g., OCU or router/switch). An optional auxiliary AC output cable maybe utilized which is a 3 meter (10 feet) sealed, shielded cable with aMIL-rated circular connector. This cable may be used to provide power toa peripheral device (e.g., OCU).

The DPA/MC may include a number of components and features. For example,the DPA/MC may include a DPA/MC enclosure assembly that houseselectrical and optical components in an environmentally sealedenclosure. The DPA/MC may also include an A/C power input that includespower cable connects to an A/C source and a power indicator such as anLED that is illuminated when A/C power is supplied. The DPA/MC mayfurther include an optical port to connect the DPA/MC to the basestation with a fiber optic cable. A first OCU port may be utilized bythe DPA/MC to connect the DPA/MC to the OCU via an RJ-45 standardconnector. A second OCU port may include an optional RJ-45 connection tocontrol the payload on the transceiver. Additionally, the DPA/MC mayinclude a data platform (WAN) port used to optionally connect the DPA/MCto a DHCP external network via an RJ-45 connection. An Ethernet cablemay be provided to connect the DPA to the OCU. In one embodiment, theEthernet cable is 3 meters long (10 feet). When present, the DPA/MCprovides electrical protection between an operator using the operatorcontrol unit (OCU) and the Base Station. The Media Converter convertsthe fiber optic signal to copper Ethernet for the OCU. The fiber opticconnection provides electrical isolation between the Base Station andthe OCU. In an alternate embodiment, the OCU is directly connected tothe base station and in such an embodiment, the electrical protectionprovided by the DPA/MC is absent.

The OCU may be a ruggedized laptop or other computing device configuredto execute an OCU application providing operation information andstatus/warning indications required for the system operation. Controlfunctions can include but are not limited to enable/disable vehicle LEDsand enable/disable high voltage. OCU application controls (visible inthe UI) may include, without limitation, buttons, sliders, or pull-downmenus that may be accessed using the computer keyboard, touchscreen (ifequipped), or mouse.

In one embodiment, the base station includes a microprocessor to managethe transmission of power and/or the collection, scheduling,computation, transmission, and receipt of data. A serial link, which mayinclude a commercially available twisted pair elevated transceivermodule integrated circuit, is capable of secure transmission and receiptof data placed on the tether.

Voltage isolation may be facilitated by a variety of techniques known tothose of ordinary skill in the art having the benefit of thisdisclosure. In one embodiment, tuned magnetically isolated windingsreject all noise and frequencies that are not within a desired MBPS(megabits per second) data transmission packet range. In someembodiments, voltage is isolated by capacitive isolation orelectro-optical isolation employing optical isolator integratedcircuits.

In one embodiment, base station may include carrier interface forconverting data received from the elevated transceiver module 2506, suchas communication data from a cellular communication established betweenan individual and one or more of antennas 2508, into a suitable form fortransit on a carrier network. As further discussed herein, the carrierinterface may be a CPRI interface or other suitable interface.

It should be appreciated, that although the discussion herein refers tothe preferable use of optical fibers for transmitting communication datafrom the receiver over the tether, other mediums may also be used. Forexample, in one embodiment, the one or more remote radio heads mayconnect via the tether to the base station using an electricalconnection in the tether composed of unshielded twisted pair (UTP)wires. In another embodiment, the communication data may be relayedwirelessly by the RRHs to the ground for communication to the carriernetwork.

FIG. 25D is an embodiment of an exemplary circular cable 2520. The cable2520 includes two or more tether conductors 2522 housed within the cable2520 to allow for ease of installation and reliability. In an exemplaryembodiment, each tether conductor 2522 is a microfilament, a pair ofthreadlike wires that may transmit over a kilowatt of power to theelevated transceiver module 2506 while also enabling transmission ofbi-directional data and high-definition video. In one embodiment, thecable 2520 may include an outer Kevlar-jacket 2524, and the tetherconductor 2522 may include a twisted copper pair with insulation thatprovides a power link and/or a communication link between the basestation 2502 and the elevated transceiver module 2506. The cable 2520may include a strength member 2526, such as synthetic fibers, tomaintain axial stiffness and break strength.

FIG. 25E is an embodiment of an exemplary flat cable 2530. The cable2530 includes two or more tether conductors 2532 housed within the cable2530 to allow for ease of installation and reliability. In an exemplaryembodiment, each tether conductor 2532 is a microfilament, a pair ofthreadlike wires that may transmit over a kilowatt of power to theelevated transceiver module 2506 while also enabling transmission ofbi-directional data and high-definition video. In one embodiment, thecable 2530 may include an outer Kevlar-jacket 2534, and the tetherconductor 2532 may include a twisted copper pair with insulation thatprovides a power link and/or a communication link between the basestation 2502 and the elevated transceiver module 2506. The cable 2530may include a strength member 2536, such as synthetic fibers, tomaintain axial stiffness and break strength.

FIGS. 25F-2511 are embodiments of a system for enabling a UAV for radiotransmission and reception of cellular communication or as an internetportal. Traditional satellite cell on light trucks (SAT-CoLTs) 2540 aredeployed, although coverage may be limited due to obstructions (terrain,buildings, flora). An UAV 2542 with CELL connectivity is deployed alongwith local SAT backhaul kits installed near a ground system, or the UAV2542 with CELL connectivity can be connected to another means of localbackhaul. The UAV 2542 includes an user equipment (UE) relay and aneNodeB. The UE relay (i.e., the fronthaul side) connects to cell towersor other backhaul mediums, and the eNodeB (i.e., the access side)provides cellular access. The UAV can include a payload having awireless antenna relay to relay cellular traffic to a call tower ortruck. The SAT-CoLTs 2540 is communicatively coupled to a satellite 2544to received data associated with, for example, the internet.

The UAV 2542 is deployed to an ideal altitude, based on environmentaland regulatory constraints, to provide the maximum coverageomni-directionally, extending a bubble of coverage below and around theUAV 2542 with CELL connectivity. The CELL connects to the local SATbackhaul, according to one or more of the embodiments shown in FIGS.25F-2511, to bridge between the newly covered mobile users 2546 and thecell network. The UAV 2542 with CELL connectivity remains on site aslong as required (as permitted by regulatory and environmentalconstraints). For example, during an emergency, local users 2546(residents, aid workers, etc.) may enter the network bubble tocommunicate with colleagues, family members, emergency services, etc.

This system provides an area where users can enter to gain cellconnectivity. For example, for large events that are relativelytemporary, UAV with CELL connectivity may be deployed to add coverageand capacity to a specific area such as a concert venue, sporting event,parade, etc.

In many cases, CoLTs are deployed to these events. The CoLTs willbackhaul via terrestrial microwave, SAT link, or ground wiredconnection. The UAV with CELL connectivity would be deployed inconjunction with the CoLTs, using them as a backhaul link.

In FIG. 25F, the UAV 2542 is tethered to a ground station 2548 andconnects to the local SAT backhaul (i.e., the STAT CoLT 2540) using awireless connection. In FIG. 25G, the UAV 2542 is tethered to (and maybe deployed from) a SAT-CoLT 2540. In FIG. 25H, the UAV 2542 is tetheredto a ground station 2548, where the ground station 2548 is backhauledthrough a hardline through the SAT-CoLT 2540.

FIG. 25I is an alternate embodiment of a system for enabling a UAV forradio transmission and reception of cellular communication or as aninternet portal. The UAV 2542 with CELL connectivity may use existinginfrastructure such as macrocells, instead of using SAT-CoLTs 2540 orthe like. In this variant, the UAV 2542 with CELL connectivity uses celltowers 2550 as the backhaul connection while continuing to distributethe local LTE bubble. The UAV 2542 may connect to the cell towers 2550via wireless communicate (e.g., LTE). As described above, the UAV 2542includes an UE relay to connect to the cell tower 2550 or other backhaulmediums and an eNodeB to provides cellular access to, for example,cellular phones of the users 2546.

Exemplary usage scenario for FIGS. 25F-25I are as follows: set up thesystem with proper perimeter and safety/regulatory precautions observed,install payload, plug in payload connector, install payload and plate,adjust antennas (if needed), launch the UAV 2542, yaw the UAV 2542 toorient, payload (if needed for backhaul), observe system performanceparameters from remote status/engineering access to CELL payload (remoteaccess may be through tether, local wireless, or cell network), adjustthe UAV 2542 or CELL parameters as needed to achieve desired systemperformance, and land the UAV 2542 when mission is complete.

FIG. 25J illustrates a safety interlock system 2560 configured to shutdown power to the tether under predefined conditions. In an exemplaryembodiment, a ground station includes a set of safety interlocks thatcan prevent circumstances where a user may be exposed to high voltage.There are physical, electronic, and software interlocks required for HVto be applied to the UAV.

Starting from Stage One 2562, all the following must be true to allowthe HV to be armed and ready to be turned on and applied: there are nosystem faults or errors 2564, communication between the Ground Station,OCU, and AV is made 2566, the stop button is not in the depressed state2568, and the HV ARM switch is in the ARMED position 2570. Once theseinterlocks are true the HV will be ARMED, which is an input for StageTwo 2572.

For HV to be applied to the UAV, Stage Two 2572 requires: the HV Armedstate to be ARMED 2574, and a user to apply the HV ON command from theOCU 2576. These interlocks will cause HV to be ON 2578 and energize theUAV via the tether.

The ground station may include additional safety mechanisms to renderthe system safe upon emergency state activation. One or more safetymechanisms are activated upon, for example, a software shutdown command,an E-STOP activation, or an error state detection. Safety mechanisms mayinclude an output crowbar (a short circuit across the HV lines in orderto bring the voltage down to safe levels as fast as possible), outputrelays (in line switches that open in case of emergency, disconnectingbase station electronics from the outside world), and E-STOP sensors.The interlock mechanism may activate safety mechanism when an accesspanel is opened/removed when an operator is performing maintenance.

The ground station may include error state detection mechanisms, such assensors that activate the safety mechanisms. Error state detectionmechanisms may include a ground shift detection sensor that detects avoltage shift in the ground level with regards to earth ground. Thisenables detection of a ground fault: when the HV lines is inadvertentlyconnected to earth ground. Error state detection mechanisms may furtherinclude overvoltage and overcurrent detection sensor, and zero-currentdetection that indicates when the microfilament has been broken ordisconnected so as to prevent exposed high voltage. Error statedetection mechanisms may also include air vehicle communicationsdetection where the air vehicle and the base station communicate uponpower up as a link in the chain to allow safe turn on (communicationspresent indicate successful filament connection).

FIG. 26A is an exemplary approach to controlling an aerial vehicle. Amulti-rotor helicopter control system 2600 receives a control signal2616 including a desired position, X in the inertial frame of reference(specified as an n,w,h (i.e., North, West, height) coordinate system,where the terms “inertial frame of reference” and n, w, h coordinatesystem are used interchangeably) and a desired rotational orientation,

$\frac{uv}{\Phi}$

in the inertial frame of reference (specified as a roll (R), pitch (P),and yaw (Y) in the inertial frame of reference) and generates a vectorof voltages

$\frac{uv}{V}$

which are used to drive the thrusters of the multi-rotor helicopter(such as multi-rotor helicopter 2710 shown in FIG. 27) to move themulti-rotor helicopter to the desired position in space and the desiredrotational orientation.

The control system 2600 includes a first controller module 2618, asecond controller module 2620, an angular speed to voltage mappingfunction 2622, a plant 2624 (i.e., the multi-rotor helicopter), and anobservation module 2626. The control signal 2616, which is specified inthe inertial frame of reference is provided to the first controller 2618which processes the control signal 2616 to determine a differentialthrust force vector,

and a differential moment vector,

, each specified in the frame of reference of the multi-rotor helicopter(i.e., the x,y,z coordinate system). In some examples, differentialvectors can be viewed as a scaling of a desired thrust vector. Forexample, the gain values for the control system 2600 may be found usingempiric tuning procedures and therefore encapsulates a scaling factor.For this reason, in at least some embodiments, the scaling factor doesnot need to be explicitly determined by the control system 2600. In someexamples, the differential vectors can be used to linearize themulti-rotor helicopter system around a localized operating point.

In some examples, the first controller 2618 maintains an estimate of thecurrent force vector and uses the estimate to determine the differentialforce vector in the inertial frame of reference,

as a difference in the force vector required to achieve the desiredposition in the inertial frame of reference. Similarly, the firstcontroller 2618 maintains an estimate of the current moment vector inthe inertial frame of reference and uses the estimate to determine thedifferential moment vector in the inertial frame of reference,

as a difference in the moment vector required to achieve the desiredrotational orientation in the inertial frame of reference. The firstcontroller then applies a rotation matrix to the differential forcevector in the inertial frame

determine its representation in the x,y,z coordinate system of themulti-rotor helicopter,

. Similarly, the first controller 2618 applies the rotation matrix tothe differential moment vector in the inertial frame of reference,

to determine its representation in the x,y,z coordinate system of themulti-rotor helicopter,

.

The representation of the differential force vector in the x,y,zcoordinate system,

and the representation of the differential moment vector in the x,y,zcoordinate system,

are provided to the second controller 2620 which determines a vector ofdifferential angular motor speeds:

${\Delta \overset{\_}{\omega}} = \begin{Bmatrix}{\Delta \omega_{1}} \\{\Delta \omega_{2}} \\\vdots \\{\Delta \omega_{n}}\end{Bmatrix}$

As can be seen above, the vector of differential angular motor speeds Δωincludes a single differential angular motor speed for each of the nthrusters of the multi-rotor helicopter. Taken together, thedifferential angular motor speeds represent the change in angular speedof the motors required to achieve the desired position and rotationalorientation of the multi-rotor helicopter in the inertial frame ofreference.

In some examples, the second controller 2620 maintains a vector of thecurrent state of the angular motor speeds and uses the vector of thecurrent state of the angular motor speeds to determine the difference inthe angular motor speeds required to achieve the desired position androtational orientation of the multi-rotor helicopter in the inertialframe of reference.

The vector of differential angular motor speeds,

is provided to the angular speed to voltage mapping function 2622 whichdetermines a vector of driving voltages:

$\overset{¯}{V} = \begin{Bmatrix}V_{1} \\V_{2} \\\vdots \\V_{n}\end{Bmatrix}$

As can be seen above, the vector of driving voltages, V includes adriving voltage for each motor of the n thrusters. The driving voltagescause the motors to rotate at the angular speeds required to achieve thedesired position and rotational orientation of the multi-rotorhelicopter in the inertial frame of reference.

In some examples, the angular speed to voltage mapping function 2622maintains a vector of present driving voltages, the vector including thepresent driving voltage for each motor. To determine the vector ofdriving voltages, V, the angular speed to voltage mapping function 2622maps the differential angular speed Δω_(i) for each motor to adifferential voltage. The differential voltage for each motor is appliedto the present driving voltage for the motor, resulting in the updateddriving voltage for the motor, V_(i). The vector of driving voltages, Vincludes the updated driving voltages for each motor of the i thrusters.

The vector of driving voltages, {dot over (V)} is provided to the plant2624 where the voltages are used to drive the motors of the i thrusters,resulting in the multi-rotor helicopter translating and rotating to anew estimate of position and orientation.

$\left\lbrack \frac{\overset{¯}{X}}{\Phi} \right\rbrack$

The observation module or sensor 2626 detects the new position andorientation and feeds it back to a combination node 2628 as an errorsignal. The control system 2600 repeats this process, achieving andmaintaining the multi-rotor helicopter as close as possible to thedesired position and rotational orientation in the inertial frame ofreference. The IMU can provide the updated sensor data or a processorreceiving data from one or more antennas can compute a signal to rotatethe vehicle into an orientation that improves signal reception andtransmission back to one or more mobile devices.

FIG. 26B is a schematic block diagram of at least one sensor used in amulti-rotor helicopter control system 2650 for controlling a UAV. The atleast one sensor includes one or more of a radar sensor 2652, aninertial measurement unit (IMU) sensor 2654, a GPS sensor 2656, a Lidarsensor 2658, a pressure sensor 2660, a gyroscope sensor 2662, and anaccelerometer sensor 2664. The data collected from the IMU sensor 2654enables the control system 2650 to track the UAV's position, i.e.,using, for example, dead reckoning, or to adjust for wind. The pressuresensor 2660 measures atmospheric pressure. Data provided by the pressuresensor 2660 enabling the control system 2650 to adjust other parameters(i.e., rotor speed, tilting angle, etc.) based on the atmosphericpressure. The gyroscope sensor 2662 measures the angular rotationalvelocity, and assists with orientation and stability in navigation. Theaccelerometer sensor 2664 measures linear acceleration of movement. Dataprovided by the gyroscope sensor 2662 and accelerometer sensor 2664 isused by the control system 2560 to compute updated linear and rotationvelocity. The radar sensor 2662 provide detection of objects, reliabledistance measurement, collision avoidance and driver assistance. Dataprovided by the radar sensor 2662 is used by the control system 2650 tocompute updated rotor speed to avoid collisions. The GPS sensor 2656provides accurate position and velocity information. Data provided bythe GPS sensor 2656 is used by the control system 2560 to computeupdated location and velocity information. The Lidar sensor 2658, whichmeasures distance to a target by illuminating that target with a laserlight, provide detection of objects, reliable distance measurement,collision avoidance and driver assistance. Data provided by the Lidarsensor 2658 is used by the control system 2560 to compute updated rotorspeed to avoid collisions.

Referring to FIG. 27, in some examples, a multi-rotor helicopter 2710 istasked to hover at a given position X and orientation in the inertialframe of reference in the presence a prevailing wind 2730. The windcauses exertion of a horizontal force,

on the multi-rotor helicopter 2710, tending to displace the multi-rotorhelicopter in the horizontal direction. Conventional multi-rotorhelicopters may have to tilt their frames into the wind and adjust thethrust generated by their thrusters to counter the horizontal force ofthe wind, thereby avoiding displacement. However, tilting the frame of amulti-rotor helicopter into wind increases the profile of themulti-rotor helicopter that is exposed to the wind. The increasedprofile results in an increase in the horizontal force applied to themulti-rotor helicopter due to the wind. The multi-rotor helicopter mustthen further tilt into the wind and further adjust the thrust generatedby its thrusters to counter the increased wind force. Of course, furthertilting into the wind further increases the profile of the multi-rotorhelicopter that is exposed to the wind. It should be apparent to thereader that tilting a multi-rotor helicopter into the wind results in avicious cycle that wastes energy.

The approaches described above address this issue by enabling motion ofthe multi-rotor helicopter 2710 horizontally into the wind withouttilting the frame of the multi-rotor helicopter 2710 into the wind. Todo so, the control system described above causes the multi-rotorhelicopter 2710 to vector its net thrust such that a force vector

is applied to the multi-rotor helicopter 2710. The force vector

has a first component that extends upward along the h axis of theinertial frame with a magnitude equal to the gravitational constant, gexerted on the multi-rotor helicopter 2710. The first component of theforce vector

maintains the altitude of the multi-rotor helicopter 2710 at thealtitude associated with the given position. The force vector

has a second component extending in a direction opposite (i.e., into)the force exerted by the wind and having a magnitude equal to themagnitude of the force,

exerted by the wind. The second component of the force vector maintainsthe position of the multi-rotor helicopter 2710 in the n,w plane of theinertial frame of reference.

To maintain its horizontal orientation Φ in the inertial frame ofreference, the control system described above causes the multi-rotorhelicopter 2710 to maintain the magnitude of its moment vector

at or around zero. In doing so, any rotation about the center of mass ofthe multi-rotor helicopter 2710 is prevented as the multi-rotorhelicopter 2710 vectors its thrust to oppose the wind.

In this way the force vector

and the moment vector

maintained by the multi-rotor helicopter's control system enable themulti-rotor helicopter 2710 to compensate for wind forces appliedthereto without rotating and increasing the profile that the helicopter10 presents to the wind.

Referring to FIG. 28, an antenna 2832 such as a sectorized antenna isattached to the multi-rotor helicopter 2710 for the purpose of capturingdata from a point of interest 2834 on the ground beneath the multi-rotorhelicopter 2710. In general, it is often desirable to have themulti-rotor helicopter 2710 hover in one place while the antenna 2832captures data. Conventional multi-rotor helicopters are unable to orientthe antenna 2832 without tilting their frames (and causing horizontalmovement) and therefore require expensive and heavy gimbals fororienting their imaging sensors.

The approaches described above obviate the need for such gimbals byallowing the multi-rotor helicopter 2710 to rotate its frame in theinertial plane while maintaining its position in the inertial plane. Inthis way, the imaging sensor 2832 can be statically attached to theframe of the multi-rotor helicopter 2710 and the helicopter can tilt itsframe to orient the imaging sensor 2832 without causing horizontalmovement of the helicopter. To do so, upon receiving a control signalcharacterizing a desired imaging sensor orientation, Φ the controlsystem described above causes the moment vector,

of the multi-rotor helicopter 2710 to extend in a direction along thehorizontal (n,w) plane in the inertial frame of reference, with amagnitude corresponding to the desired amount of rotation. To maintainthe position, X of the multi-rotor helicopter 2710 in the inertial frameof reference, the control system causes the multi-rotor helicopter 2710to vector its net thrust such that a force vector

is applied to the multi-rotor helicopter 2710. The force vector

extends only along the h-axis of the inertial frame of reference and hasa magnitude equal to the gravitational constant, g. By independentlysetting the force vector

and the moment vector

, the multi-rotor helicopter 2710 can rotate about its center whilehovering in one place.

As is noted above, conventional multi-rotor helicopters are controlledin roll, pitch, yaw, and net thrust. Such helicopters can becomeunstable (e.g., an oscillation in the orientation of the helicopter)when hovering in place. Some such helicopters include gimbaled imagingsensors. When a conventional helicopter hovers in place, its unstablebehavior can require that constant maintenance of the orientation ofgimbaled imaging sensor to compensate for the helicopter's instability.

Referring to FIG. 29 and FIG. 30, a modular aerial vehicle system allowsfor simple, modular switching between a number of differentconfigurations, including a free-flying, battery powered configurationand atethered configuration.

In some aspects, an aerial vehicle (e.g., the aerial vehicle describedin PCT/US2015/033992, and also in corresponding U.S. application Ser.No. 15/316,011, filed Jun. 3, 2015, “FIXED ROTOR THRUST VECTORING” whichis incorporated herein by reference) includes a receptacle or “modulebay” in its fuselage for receiving modules for configuring the aerialvehicle. One example of a module that can be received by the module bayis a battery power configuration module for configuring the aerialvehicle into a battery operated mode. In some examples, the batterypower configuration module includes a battery (e.g., a lithium ionbattery) and circuitry associated with battery power management. In someexamples, the battery power configuration module includes terminals thatcorrespond to terminals located in the module bay such that, when thebattery power configuration module is inserted into the module bay, theterminals of the battery power configuration module are in contact withthe terminals in the module bay (e.g., for power transfer).

Another example of a module that can be received in the module bay is atethered configuration module. The tethered configuration moduleincludes or is attachable to a lightweight tether for connection to aground station, data linkage connectors which enable use of the tetheras both the power conduit, and conveyance mechanism for command andcontrol communications and telemetry return, for vehicles equipped toenable hardwired interface with their ground-based operator. In someexamples, the tethered configuration module supplies power informationto the user via established vehicle health monitoring strategies, suchthat continuous feed of power from the ground is properly reported, andany battery life-related behaviors (like land on low power) areprecluded.

In some examples, the tether is spooled (e.g., deployed from and/orre-wound into) in a body of the tethered configuration module. In otherexamples, spooling of the tether occurs at a ground station.

In some examples, the tethered configuration module includes terminalsthat correspond to terminals located in the module bay such that, whenthe tethered configuration module is inserted into the module bay, theterminals of the tethered configuration module are in contact with theterminals in the module bay (e.g., for power transfer, command andcontrol information transfer, sensor information transfer, etc.).

In some examples, a multi-use module is a hybrid tethered configurationmodule and battery power configuration module (i.e., a module includingboth tether hardware and a battery). When in use as a free flyingvehicle, the tether is disconnected from the multi-use module (leavingthe tether management hardware intact), and a battery unit installed inthe multi-use module. When being used in a tethered configuration, thebattery unit is removed from the multi-use module, and the tether isattached. In some examples, the multi-use module is used with both thebattery unit installed and the tether attached. In such examples,circuitry for intelligently switching between battery power andtether-based power is included in the multi-use module.

In some examples, the aerial vehicle includes minimal or no powerconversion, telemetry, vehicle command and control, sensor, orcommunications circuitry. That is, the aerial vehicle includes only afuselage, including spars with thrust generators disposed at their endsand terminals for connecting the thrust generators to an electronicsmodule in the module bay. The electronics module may include a computingcircuitry (e.g., a processor, memory) and/or discrete circuitry forpower conversion, telemetry, vehicle command and control, andcommunications. The electronics module can be swapped in and out of oneor more aerial vehicles.

In some examples, different modules can include different sensor suitesand/or different functions to adapt the aerial vehicle to its mission.For example, the unmanned aerial vehicle may include a sensor modulewithin the module bay for configuring the unmanned aerial vehicle toreceive sensor data. In other embodiments, the unmanned aerial vehiclemay include a radio communications module within the module bay forconfiguring the unmanned aerial vehicle to receive radio communications.In still other embodiments, the unmanned aerial vehicle may include amulti-use module that includes one or more of the tethered configurationmodule, the battery power configuration module, the sensor module, theradio communications module, and the electronics module.

In general, all of the modules that can be received by the module bay,including the tethered configuration module, the battery power module,the sensor module, the radio communications module, and the electronicsmodule have the same form factor, and fit without additionalmodification, into the module bay of the aerial vehicle. The module baycan be located on a top or a bottom of the fuselage of the aerialvehicle.

In some examples, modules can be designed to retrofit pre-existingaerial vehicles. For example, a tethered configuration module may beconfigured to fit into a bay or attach to standard attachment points ofa pre-existing aerial vehicle and to provide tethered power to theaerial vehicle. In some examples, such a tethered configuration moduleincludes an RF transponder for receiving command and control informationfrom a ground station via the tether and transmitting RF command andcontrol information to the pre-existing aerial vehicle. The tetheredconfiguration module may also include power conversion and conditioningcircuitry for converting and conditioning the power received over thetether into a form that is usable by the aerial vehicle.

In some examples, the modular aerial vehicle system includes a groundstation including one or more of a generator for generating power, abase station for conversion of the power from the generator fortransmission over the tether and for communicating over the tether, anda spooler for managing an amount of deployed tether. One example of sucha ground station is described in U.S. Pat. No. 9,290,269, “SPOOLER FORUNMANNED AERIAL VEHICLE SYSTEM,” which is incorporated herein byreference in its entirety.

In some examples, one or more elements of the ground station is attachedto a moving vehicle such as a commercial vehicle, constructionequipment, military equipment and vehicles, boats and personal vehicles.

Aspects may include one or more of the following advantages.

Switching between battery powered operation and tethered operation is asimple modular switching operation. System flexibility is increased.Functionality and data capture capabilities are increased. Both theadvantages of tethered systems (e.g., persistent, secure communications,flight duration unconstrained by on-board battery energy capacity) andfree flying systems (e.g., wide range of motion, unconstrained by tetherlength) are achieved in a single system.

Other features and advantages of the invention are apparent from thefollowing description. FIG. 29 shows installation of a battery poweredconfiguration module into the modular aerial vehicle system. A modularaerial vehicle 2940 includes a module bay 2942 configured to receive amodule 2944. The module 2944 is a battery power configuration module andincludes a battery 2946. When the battery power configuration module2944 is received in the module bay 2942, the modular aerial vehicle 2940is configured in a battery powered, ‘free-flight’ mode 2960.

FIG. 30 shows installation of a tethered configuration module into themodular aerial vehicle system. The modular aerial vehicle 2940 receivesa tethered configuration module 2948 including a tether 2950 in itsmodule bay 2942 to configure the modular aerial vehicle in a tethered,ground powered mode 2952.

Referring to FIG. 31A tethered system can employ operating lights toincrease visibility and can also be used to determine vehicle location.The tether 3102 can have a disc 3104 statically mounted at a fixedlocation relative to the vehicle where spaced light emitters 3106 suchas LEDs can be strobed around the perimeter to emit light 3108. Thelight emitted by system 3100 can also be detected by detector mounted ona ground station, for example, that provide position data to the vehicleto update the vehicle position.

FIG. 31B illustrates tether markers for an air vehicle, according to anexemplary embodiment. In an exemplary embodiment, the tether markers arean array of LED strobe lights 1902, as shown in FIG. 19a . The array ofLED strobe lights 1902 are hung at intervals (i.e., 50 foot intervals)on the tether. The LED array may contain multi-lit color lights as wellas IR. In this case, the LED arrays could get their power from a batteryor from the air vehicle.

In still further embodiments, the LED array may be made into a small,lightweight and aerodynamic package. The package may contain aretractable leash 1906 such that the arrays may be arraigned together toform a “puck,” as shown in FIG. 19b . The leash 1906 have a connector onan end that mates with the air vehicle providing it with power for thelights and a signal for the light pattern. The puck 1904 may have areceptacle or connector 1908 on the underside to accept the leash 1906of a lower puck. The pucks 1904 can be linked together with theirleashes 1906 retracted on the ground and when the air vehicle takes off,it will pick up the first puck 1904 by its leash 1906. As the airvehicle goes higher, the second puck 1904 is lifted by the first, and soforth. The retracting leash 1906 system of each puck 1904 will preventany tangling during launching and landing.

The puck 1904 includes an array of strobe lights 1902 facing outward ona toroid resembling a donut; control and power electronics to drive thestrobe lights 1902; a leash 1906 to provide structural support for thepuck 1904 and power/signal for the strobes; a retraction mechanism forthe leash 1906, which could take the form of a passive dog leash 1906 orbe powered like in the spooler; receptacle on the bottom for the lowerpuck 1904 to connect; a tether attachment point on the side of the puck;and aerodynamic faring.

FIG. 31C shows the strobe lights 1902 positioned in increments aroundthe perimeter of the puck, with a lens to provide a beam angle suitableto allow them to overlap so that the puck 1904 is visible from anyangle. A retraction mechanism is mounted in the center of the puck. Theretraction mechanism includes a large diameter spool to hold the 50 feetof leash 1906. A rotating arm with a pulley on the end that travelsaround the spool, and either a motor or a spring to rotate the arm. Themotor drives the retraction.

On the side of the puck 1904 is a loop to run the air vehicle tetherthrough. By attaching the puck 1904 to the tether, the puck 1904 shouldremain downwind of the tether and the entanglement of the leash 1906 andtether is minimized.

The operation of using the pucks 1904 is as follows: A stack of pucks1904 (number required for the mission) are positioned on the spoolerwhere they are each plugged into the one above and the upper most isplugged into a payload or other connector on the air vehicle. The airvehicle takes off and begins to ascend. As is does so, the leash 1906 ispulled from the first puck, either winding up a spring, or backdrivingthe unpowered motor. When the end of the leash 1906 is reached, the puck1904 is lifted into the air. At this point, the second puck 1904 beginsto unwind its leash 1906 until it too is lifted into the air. When theair vehicle is at final altitude, all of the pucks 1904 is suspended bytheir leashes 1906. The tether markers are visible from distance, forexample, one mile in daylight.

When landing, the last puck 1904 to leave the ground is the first toreach the ground. During a landing phase of flight, power is provided tothe pucks 1904 motors (if equipped) such that they retract the tether.The motor may not need be strong enough to lift the puck, but only towind the leash 1906 back in after the puck 1904 reaches the ground. Asthe leash 1906 is coming down, the motor will wind it back up. If aspring is used, it will need to be strong enough to overcome frictionand draw in the leash 1906. When the air vehicle has landed, all of thepucks 1904 is on the ground with the leash 1906 retracted.

In other embodiments, the tether markers include one or more lightsconfigured to emit light continuously or at predetermined times. Inanother embodiment, the tether markers are flags or pennants located ona tether at predefined locations, for example, every 50 feet above 150feet above ground level (AGL).

In additional embodiments, electroluminescent (EL) wire may beintegrated into the tether. The EL wire may be powered and/or controlledfrom the air vehicle. The EL wire may be bright enough for nighttimeuse. In some embodiments, the EL wire may produce IR light for nightvision systems.

Referring to FIG. 32 illustrates a process flow diagram 4000 of anetworked system using both tethered and untethered UAVs. The UAVs canbe separate types of vehicles, or they can be of a modular design asdescribed generally in the present application. In the embodiment ofFIG. 32, the method includes operating 4002 one or more UAVs having atleast four rotors to navigate a flight path in either a tethered oruntethered operating mode in response to an onboard flight plan or inresponse to commands distributed by a network controller.

A first UAV can be launched after mounting 4004 a first module having abattery to the first UAV to operate in a tethered flight mode whereinpower can be switched between the battery and the tether. The tether canbe operated using embodiments of the tether management system asdescribed previously herein.

The first UAV can be operated from its separate control station, oroptionally, by connecting 4006 the first UAV to a communications networksuch as a cellular network (3G/4G) or a wired Ethernet via the tether,the network operating one or a plurality of UAVs.

For many applications it is critical to have updated accurate positiondata for each UAV to perform flight or payload operations such asvehicle tracking as described previously herein. Updating position data4008 of the tethered UAV can using a GPS sensor mounted to the UAV, acomputed position based on stored IMU data, or position data from anexternal source delivered to the UAV with the tether or by wirelesslink.

The networked system can also employ untethered UAVs. These can besmaller UAVs, such as those shown in FIG. 29, for example, where asecond module having a battery to operate the UAV solely on batterypower can be mounted 4010 to the UAV. The second module optionallyincludes a radio and/or a sensor array. The sensor array can furtherenable autonomous operation by utilizing software modules that canidentify and monitor objects on the ground or in the flight operatingspace and provide anti-collision flight control algorithms. Theuntethered UAV can be operated in a fully autonomous mode, under pilotcontrol from a ground station or by wirelessly communicating 4012 withthe network. It is also critical for untethered vehicles to have correctposition data for flight control and payload operations, particularly inGPS denied environments as described herein. The position data of theautonomous (untethered) UAV can be adjusted 4014 by using a GPS sensormounted to the UAV, a computed position based on stored IMU data orposition data from an external source by wireless link from the networkor by optical or radio communications from other nodes in the networksuch as control stations on the ground, on vehicles, or from other UAVsas described previously herein.

Portions or all of the embodiments of the present invention may beprovided as one or more computer-readable programs or code embodied onor in one or more non-transitory mediums. The mediums may be, but arenot limited to a hard disk, a compact disc, a digital versatile disc,ROM, PROM, EPROM, EEPROM, Flash memory, a RAM, or a magnetic tape. Ingeneral, the computer-readable programs or code may be implemented inany computing language.

Since certain changes may be made without departing from the scope ofthe present invention, it is intended that all matter contained in theabove description or shown in the accompanying drawings be interpretedas illustrative and not in a literal sense. Practitioners of the artwill realize that the sequence of steps and architectures depicted inthe figures may be altered without departing from the scope of thepresent invention and that the illustrations contained herein aresingular examples of a multitude of possible depictions of the presentinvention.

The foregoing description of example embodiments of the inventionprovides illustration and description, but is not intended to beexhaustive or to limit the invention to the precise form disclosed.Modifications and variations are possible in light of the aboveteachings or may be acquired from practice of the invention. Forexample, while a series of acts has been described, the order of theacts may be modified in other implementations consistent with theprinciples of the invention. Further, non-dependent acts may beperformed in parallel and equivalent embodiments may be combined orseparated in a manner not specifically discussed herein.

1. A base station system for controlling an unmanned aerial vehicle(UAV), the base station system comprising: a tether connectable to theUAV and configured to provide data communication and power to the UAV;and a portable base control housing including: a base station controlsystem having at least one data processor and a direct current (DC/DC)converter, the base station control system configured to control, usinga plurality of adjustable operating parameters, transmission of powerand data signals to the UAV with the tether, wherein at least one of theplurality of adjustable operating parameters comprises a datatransmission rate.
 2. The system of claim 1, further comprising: anEthernet switch disposed within the portable base control housing andconfigured to control data communication with the UAV, wherein the atleast one data processor comprises a central processing unit connectedto the Ethernet switch; one or more programmable gain amplifiersconfigured to control a signal level of signals transmitted with thetether; and a plurality of digital to analog converters to couple analogsignals to the tether, wherein the portable base control housingincludes one or more air inlets from which to receive air into theportable base control housing and one or more air vents from which toexpel air from the portable base control housing.
 3. The system of claim1, further comprising: a heat control mechanism located within theportable base control housing, wherein the heat control mechanismcomprises: a thermally conductive plate; and a fan configured to deliveran air flow to provide forced convection within the portable basecontrol housing; and a display control unit comprising: a display; and agraphical user interface configured to display a plurality of displaywindows; and a tether retainer mounted on a first side of the thermallyconductive plate, wherein the base station control system is mounted ona second side of the thermally conductive plate.
 4. The system of claim3, further comprising: a temperature sensor within the portable basecontrol housing to monitor air temperature; a servo configured tocontrol the air flow by adjusting a first portion and a second portionof the air flow based on a monitored air temperature; and one or morehigh voltage transformers connected to the portable base control housingand configured to isolate an electrical charge, wherein the firstportion of the air flow is directed to exit radially from the tetherretainer and the second portion of the air flow is directed to the basestation control system, wherein the tether retainer comprises a fixedspool, wherein the tether comprises one or more lights configured toemit light, wherein the tether includes a Kevlar layer extending with atwisted pair of wires, and wherein the portable base control housingweighs 28 kilograms or less.
 5. The system of claim 3, wherein theplurality of display windows comprises: a first display windowconfigured to display a position of the UAV in a flight operationalspace, and at least a second display window configured to display one ormore of the adjustable operating parameters; and wherein the basestation control system is configured to adjust the adjustable operatingparameters for different payloads that operate on the UAV.
 6. The systemof claim 1, wherein the tether includes one or more optical fibers,wherein each optical fiber is connected to at least one transmitter andone receiver, wherein the tether and the portable base control housingare configured to provide 500 volts or more to the UAV, and wherein theUAV is configured to receive location data of the UAV from the tetherwhen operating in a GPS-denied mode.
 7. The system of claim 1, furthercomprising a tether retainer that comprises a moveable arm, wherein themoveable arm is rotatable by a spindle connected to a motor, wherein adistal end of the moveable arm is operable to wind the tether onto astationary spool and/or dispense the tether from the spool by rotationof the arm about the spool, and wherein a tether management system isconfigured to operate without a slip ring.
 8. The system of claim 1,further comprising: a pivoting hoop attached to the UAV and configuredto swing on one axis, the pivoting hoop including a movable attachmentfor the tether; and a humidity sensor disposed within the portable basecontrol housing, the humidity sensor communicatively coupled to a heatcontrol mechanism within the portable base control housing, wherein theportable base control housing is configured to be mounted on a vehicle,wherein the vehicle comprises one or more ground attachments configuredto dissipate excessive electrical charge, and wherein the portable basecontrol housing is positioned in a recessed compartment on the vehiclethat includes a retractable top surface over the recessed compartment.9. The system of claim 1, further comprising a power management circuitconnected to the DC/DC converter on the UAV and to a battery on the UAV,wherein the power management circuit is configured to supplement powerfrom the tether with power from the battery, wherein the powermanagement circuit comprises a sensor configured to measure at least oneof a power level from the tether or a power level from the battery, andwherein the UAV has a startup sequence using power from the battery. 10.The system of claim 9, wherein the power management circuit comprises aY board, wherein the UAV has a payload mechanism configured to receiveone or more payloads, wherein the one or more payloads are configured toreceive power and data from the UAV, wherein adjustable parametersettings correspond to different payloads, and wherein the tether andthe base station control system are configured to deliver more than 1000volts to the UAV.
 11. An unmanned aerial vehicle (UAV) systemcomprising: a UAV having a data processor, wherein the data processor isconfigured to control a plurality of adjustable operating parameters ofthe UAV; a tether connectable to the UAV, wherein the tether isconfigured to provide data communication and power to the UAV; and apower management system on the UAV that is connectable to the tether anda battery to control power usage of the UAV.
 12. The UAV system of claim11, further comprising an Ethernet switch disposed within a portablebase station housing, wherein the portable base station housingcomprises a base station controller having at least one processor, andwherein the base station controller has a plurality of adjustableoperating parameters to control a corresponding plurality of flightoperations of the UAV and to control the data communication with theUAV.
 13. The UAV system of claim 12, further comprising: a heat controlmechanism located within the portable base station housing, wherein theheat control mechanism comprises: a thermally conductive plate; and afan configured to deliver an air flow to provide forced convectionwithin the portable base station housing; and a tether retainer mountedon a first side of the thermally conductive plate, wherein the basestation controller is mounted on a second side of the thermallyconductive plate, wherein the air flow is directed to exit radiallythrough radial openings in the tether retainer, wherein a moveable armis configured to rotate on a spindle driven by a motor under thethermally conductive plate, and wherein the spindle is configured torotate the arm about a spool positioned about the thermally conductiveplate.
 14. The UAV system of claim 12, further comprising a sensorconfigured to monitor at least one of a power level of the tether or apower level of the battery, wherein a first operating parameter of theplurality of adjustable operating parameters comprises a datatransmission rate, and wherein the power management system comprises apower management circuit configured to supplement power provided withthe tether using battery power.
 15. A method of operating a base stationunmanned aerial vehicle (UAV) system, the method comprising: connectinga tether to a base station, wherein the tether is connectable to a UAVand provides data communication and power to the UAV; controlling atether management system having a moveable arm that deploys the tetherfrom a tether retainer during flight of the UAV; and controlling, by abase station controller having at least one processor and a powersource, a plurality of adjustable parameters that control operation ofthe UAV.
 16. The method of claim 15, further comprising: operating anEthernet switch disposed within a portable housing to control the datacommunication with the UAV; communicating with the UAV using one or moreoptical fibers; operating one or more high voltage transformersconnected to the portable housing; and delivering 1000 volts or more tothe UAV with the tether and the base station controller, wherein thetether comprises one or more optical fibers for transmitting data, andwherein each optical fiber is connected to at least one transmitter andone receiver.
 17. The method of claim 15, further comprising:controlling a temperature of the tether retainer with a heat controlmechanism located within a portable housing, wherein the heat controlmechanism comprises a thermally conductive plate; rotating the moveablearm about a stationary spool mounted above the thermally conductiveplate, wherein the tether retainer is mounted on a first side of thethermally conductive plate and the base station controller is mounted ona second side of the thermally conductive plate; and operating the UAVwith the portable housing mounted on a vehicle, wherein the portablehousing is positioned in a recessed compartment on the vehicle thatincludes a retractable top surface over the recessed compartment, andwherein the plurality of adjustable parameters comprise one or more of atether length, a spooler rate, a payload weight, or an altitude of theUAV.
 18. The method of claim 17, wherein the heat control mechanismfurther comprises a fan, wherein the controlling the temperaturecomprises: measuring the temperature with a temperature sensor withinthe portable housing; operating a servo to control an air flow byadjusting a first portion of the air flow and a second portion of theair flow based on a monitored temperature; delivering, by the fan, theair flow to provide forced convection within the portable housing, theair flow passing above the thermally conductive plate; and wherein themethod further comprises: operating the portable housing mounted on thevehicle, the portable housing including a tension sensor that measurestension of the tether, wherein the tether includes a Kevlar layerextending with a twisted pair of wires; providing, by the tether and thebase station controller, 200 volts or more to the UAV; and displaying,by a display control unit having a display and a graphical userinterface, a position of the UAV in a flight operational space with afirst display window and one or more of the adjustable operatingparameters in at least a second display window.
 19. The method of claim15, further comprising: operating the UAV with the base stationcontroller in a portable housing that weighs 28 kilograms or less;selecting a data rate transmission rate of at least 5 Mbps, at least 12Mbps, or at least 40 Mbps; and dispensing or winding the tether on thetether retainer that comprises a fixed spool.
 20. The method of claim15, wherein the base station controller comprises a direct current(DC/DC) converter, the method further comprising: operating the basestation controller to control, using at least one adjustable operatingparameter, transmission of power and data signals to the UAV, whereinthe at least one adjustable operating parameter comprises a datatransmission rate; controlling a signal level of signals transmittedwith the tether with one or more programmable gain amplifiers; operatinga plurality of digital to analog converters to couple analog signals tothe tether; and adjusting one or more operating parameters for differentpayloads that operate on the UAV.